8 med errors is a LOT. I've made one in five months- I gave 1mg of Dilaudid and not 0.5mg. The pt tolerated it well and honestly, 1mg would have probably made more sense to order on this lady anyway. BUT- what are your errors? Is it the wrong pt? Wrong med? Wrong dose? You have to check and double check. After that one error, I sit down and look at the computer right before I walk into the room to check the name and check the meds and doses. If I'm giving something I don't usually give, I check right before I pull it up and sit down to check again to make sure I have exactly what I need to give in my hand.
You are definitely not too far in to be asking questions! You've been a nurse for FIVE months! Find a handful of nurses and explain to them how you feel and tell them you'd really like them to help you understand things. I'm lucky because I've had one preceptor for the last 4 months and she is AWESOME! I get my heart meds mixed up with beta blockers and CCB and reducing preload and afterload and blah blah blahhhhh... I still have to ask a lot, "Okay, I'm giving Lopressor- this is the BP and this is the HR- is this okay?" since those meds just don't stick in my head and I don't want to bottom out my patients. I know which nurses at work I can ask questions to and not feel like an idiot. ASK ASK ASK. It's how you learn.
By now, you probably should understand what it means if the HR is 120. But you have a lot of years ahead of you so if you don't, you just need to ask and learn. When a nurse explains it, ask some more questions so you know exactly what's going on. I even sometimes preface my questions with, "I know I've learned this, but I get confused sometimes. Can we just go over this again?"