Based on your original post, I get the impression that your previous experience was as a CNA or some other nursing support staff. If that's the case, you may have felt -- in school -- that gave you an edge, because it probably did, especially in clinicals. Otherwise, as someone else said, I don't see how you could have 2 yrs experience but only 6 months on your first job.
Here's the thing: wherever you go, you will work with experienced nurses, some of whom will be bitter, nasty, unpleasant people, and enduring their presence will be a chore, if not sheer agony. They will not be up to date on everything, maybe not on most things. Maybe they graduated 20 or 30 years ago and haven't picked up a book since except for required continuing education and certifications.
That doesn't mean you can't learn from them. Every experienced nurse, no matter how much you can't stand them, probably has something to teach you. You just have to be OPEN to this -- and you have to ask. You can even learn from the CNA's/nurse's aides -- IF you're open to it.
By thinking that you were completely on top of things and handling it, you were closed off to learning from experienced coworkers. When people sense you're closed off to them, they close you off.
Nursing is a people oriented job. Your ability to get along with people (coworkers as well as patients) is just as important as your knowledge, experience, clinical expertise, etc. -- maybe more important. That is the foundation on which your work experience will be based, because nursing is a team sport.
If you act like a lone wolf, you will be treated as one; you'll have no support from your coworkers. They will give you enough rope to hang yourself -- and it sounds like that is what happened.
A normal reaction for a brand new grad -- at least, one who doesn't think he or she knows everything -- would be to ASK another, experienced nurse, "Can I use my scissors to cut a pill if I can't find the pill cutter?" New grads are famous for asking dozens of seemingly obvious (and annoying) questions of their more experienced coworkers.
It's not the fact that you did it that matters, it's the fact that you didn't even bother to ask anyone if that was okay to do. Had you asked, coworkers might have told you not to do it, or might have told you where the pill cutter was.
The big question is: why didn't you ask?
You don't mention your preceptor. Did you have one? Or did you get paired up with whoever was most experienced on your shift? If the hospital kicked you out onto the floor, on your own, after only 6-8 weeks of orientation, a) that was too little, and b) you should have asked for more, not happily gone off on your own as if you weren't a new grad.
Not asking coworkers, not mentioning your preceptor -- to me, these are red flags. I'm utterly perplexed that with six months on the job you actually believed you were handling things and were as confident as you say you were. All the new grads I started with were as bumbling and confused and constantly uncertain as I was, constantly feeling like they weren't cutting it, and afraid they'd picked the wrong career. (We were hired directly into ER as new grads.) We were stressed, we were prone to backing off and letting the experienced nurses take over when we got critical ambulance runs, we were about as UNconfident as you could be.
An experienced nurse, the sister of one of my fellow new grads, told us this: In your first year, your first job, you just do what you're told, and you don't understand why you're doing it. By the second year, you still do what you're told, but you start to understand WHY you're doing what you're told to do.
And that is pretty much how it went for us. I didn't feel really confident until my third year on the job. So I can't understand how you could have felt as confident as you did. That's just... bizarre to me.
It sounds like your perception of your abilities was very different from others' perceptions of your abilities, and that the gap between them was widening as time passed. That kind of a disconnect is troubling. As others have said, you need to think about how and why all this happened.
If your hospital is part of a chain, being fired at one in the chain means you can't get hired at others. You have a tough row to hoe, here. Most hospitals do not want to hire nurses who worked less than 1 year in their first job.
Agencies will hire you, but be aware that agency nurses are often thrown into assignments with little or no orientation to the hospital or unit, and expected to hit the ground running. You may also be resented as an agency nurse, which means coworkers will be less likely to help you out. (You may also be welcomed at highly understaffed facilities; it's not all bad.)
If you are resented, you will not have as much opportunity to absorb "by osmosis" the knowledge and tips experienced nurses could give you. Despite that, DO NOT tell your coworkers that your experience is less than a year unless you've known them for at least a few months and you truly feel you can trust them. Most staff nurses are (understandably) suspicious of agency nurses, because in many facilities, agency nurses do not have good reputations and are not considered good nurses. Many people think that agency employees (whether nurses, pharmacists, or physicians) "couldn't cut it" in a staff position at a hospital, or can't get hired as staff somewhere because of bad references or lack of experience. In your case, that would be at least partly true.
You're between a rock and a hard place. It's hard to see how you got here except by your own behavior. Your best option -- which is not a good option, but it's maybe the only option -- is to seek agency work. Apply to as many nursing jobs as possible at hospitals not affiliated with the one you were fired from. But, the economy is only slightly better than it was, so you will likely face an uphill battle trying to get a staff position.
As others have suggested -- you need to reflect on this experience. Defensiveness is natural as your initial reaction to getting fired. But don't wallow in defensiveness. You really need to examine your own actions, every step of the way during those first 6 months, in order to see where you started to go wrong. Because it probably was a number of little things at first that started to accumulate before the write-up over using scissors to cut a pill.
In addition to cultivating some humility, you need to develop better people skills. This is especially true if you're a male RN surrounded by females, because then you're not only dealing with people, but gender specific communication differences. I worked in IT for 12 years before being laid off and going to school for nursing. I was used to working with nearly 100% men. When I started my first nursing job out of nursing school, working with nearly 100% women was a huge culture shock for me. Huge. Especially since I was never particularly 'one of the girls' because I had been 'one of the guys' for so long.
All of that nonverbal communication stuff they taught you in nursing school or any transcultural nursing classes you may have taken -- it's not just useful for working with patients. It's necessary for getting along with your coworkers. You need to be able to recognize people's social cues and clues. I suspect there were many that you blew past before the write-up and before the firing.
Good luck.
ETA: Forgot to say, agency nurses also sometimes get the heaviest work loads and assignments, the most complex patients. Staff nurses often figure, "Let him/her have this train wreck; they're getting paid more than me anyway." I say this having worked both as a staff nurse AND as an agency nurse (and as an agency nurse that got hired on as staff after a 3 month contract assignment). That's just the way it goes. But, like I said, it's not all bad. Some chronically understaffed hospitals are profoundly grateful to have the help, and some staff nurses are too, because then they get breaks and lunches they might otherwise not get if there weren't agency nurses helping out.
