I may be wrong about this, but it does sound like you don't want to follow in your mom's footsteps. If that's the case, then I think you should try out this A&P class, just to see if it peaks your interest. The 4-year wait list does suck, but as umbdude said, maybe it will take a few years for you to really be ready for the program. You should check with that school to see what their policy is on the expiration of science classes (I think most programs want you to take your sciences within 5 years of starting). As long as the A&P class wouldn't expire before you started the program, I say go for it and take it this summer.
Honestly, I think it could be a turning point for you - either you'll love it and it will motivate and inspire you to keep pursuing this path, or you will hate it and it will let you know that this field isn't for you. I decided to pursue my MBA early last year because I thought that was really what I wanted to do. I took a Marketing class and realized in a short amount of time that I really didn't have much interest in the field. It was then that I did some soul searching and realized that I wanted to pursue Nursing. So I don't really have any regrets about taking that class, even though it could be viewed as a "waste of time." If I hadn't taken the class, I might not have realized what my true passion was. I'm 28 right now and it's taken me a very long time to figure things out. I even have a B.A. in a whole other field (Law & Justice Studies) because I thought I had to have my life figured out at 22. It's ok to take your time and try various fields in order to find out what you enjoy. That's what I did!