I want to start out by saying that I was a psych/neuro major who decided in sophomore year to add a chem major, so when I saw the title of your thread I thought "HELLS YES" and clicked. But after reading your situation, though, I think that it might be a bad idea. Here's why:
1. You don't sound like you're that thrilled about chemistry. Upper level chem classes are disgusting and filled with people who are really into it. They will be difficult and if you're not into the material, disastrous for your GPA, which will cancel out any glamour you get from the double major--if any, since as a former poster mentioned, bio/chem is hardly an interesting combo.
2. If you're already graduating in 4 1/2 years, it makes more sense to take that half a year and do something that is enjoyable to you or even to work a job that will teach you things your academic environment will not. At the minimum you won't have to pay the extra tuition + the opportunity costs of a job.
3. If you feel like you would regret not having tried this out, go check out or borrow the pchem textbook and see how you feel about it. When I got my pchem textbook I was ecstatic (seriously). If you look through it and think "holy crap wtf" then chemistry is not for you.
people seem to be impressed by pchem though. First thing one of my interviewers said to me was "before we start, I just wanted to say... Nice pchem grades". it seemed to overshadow my incompetence in biochemistry.
This is so reassuring haha
What is p-chem useful for in med school? Radiology maybe?
Haha I'm not sure anybody uses pchem in real life, but it *definitely* helped me with studying for the physical science section of the MCAT.