Boy, do I feel what you are saying! I just graduated in Dec 2010 at the age of 42, I turned 43 in January, took my boards a week after my bday and started working as a RN a few days later. Like you I feel like nursing school did not prepare me for "the real world".
I got 12 weeks of orientation on day shift, only to find out that I was going to nights. So I asked for more orientation for nights. I got an additional 2 weeks with the option to go longer if I felt I needed it. I didn't ask because I knew I would never "feel ready" so I just bit the bullet.
I have come to understand that it's going to take me a long time to feel comfortable if ever. And that I need to speak up, not let the "older" nurses take advantage of me and to not be afraid to ask questions! Take advantage of their wisdom and knowledge. I ask questions all the time. I'm sure I get on the other RNs nerves but hey, I'd rather do that than harm my patient.
Don't be afraid to ask the docs questions too. Some of them love to teach. Listen to them, you will learn alot.
I'm not sure if your hospital has a Mentor Program. Mine does for new grads and it's wonderful. I am able to call/text/email/go see my mentor for any reason - to whine, cry, celebrate, etc. If you have a mentor (preferably another RN that is not associated with your floor) take advantage of having them there for you and listen to their wisdom, advice, etc. It is well worth it.
Good luck to you (and to me! LOL)