What have I gotten myself into? (some venting)

Well I've started with my upgrading. Bio 12 and Math 10. I had my math...but my mark wasn't "good enough"...so I have to work on it. I thought I had Bio 12...but didn't. So now I'm in the process of trying to get back into the mindset of doing homework and studying. I have one thing to say about it so far...I HATE IT!!!!!!! I just read the first chapter in my bio textbook, then tried to answer the questions in the study guide. I had no clue what they were talking about...well pretty much anyways. I couldn't answer a darn question right! I knew this was going to happen and it scares the crap out of me to think that I want to be a nurse! I have so many doubts about this, and this is only the beginning and I'm feeling overwhelmed about it all. I've never been the scholarly type...never. So school intimidates me. I mean I wasn't a bad student...but I wasn't the greatest either. I don't enjoy reading because what I read doesn't ever seem to sink into this brain of mine!! I hate it. Its so frustrating. It makes me feel very helpless and hopeless about my future in nursing. I knew this was going to happen. It makes me sad. I wish I loved school, loved learning new things...which I do in some respect...but not like some (my sister!!). I wish things came easy for me, and some things do...but obviously others don't! Plus I can see that this is going to be very hard on my family...me studying every evening. It makes me doubt whether or not this is a good idea. I've wanted to do this for a few years now...but maybe I should wait a bit longer. I don't know. I'm just so unsure right now. I know that I have little faith in myself when it comes to succeeding...thats something that I need to change...but how? I'm just really upset about this all right now...I feel that I've gotten myself in over my head!