biotin is the only vitamin that is proven to make hair grow, so check for that in your multivitamin. you can also just get biotin pills at CVS or wherever.
i've never heard of this side effect before--although ugggh, now im going to be paranoid. I've been on adderall for years though, 20 mgs or more and have not noticed it. it sounds like you are definitely sensitive to it. i have noticed when i'm on adderall that i get obsessive about tweezing my body hair, and also comb/touch my hair more frequently. Is it possible you're doing this without realizing it? That could make it fall out more.
if you need to continue taking the adderall:
i would take lots of vitamins (check for biotin!), eat a diet high in omega-3s & 6s, wash and brush your hair sparingly, only use a wide-tooth comb when it's wet. use shampoo and conditioner for thinning hair. Nioxin is well known brand with treatment for mild
hair loss.
http://www.nioxin.com/en/home.aspx
take the adderall as sparingly as possible too, and definitely bring it up to your doctor. s/he may be able to offer you solutions that don't involve you stopping your meds.