It sounds like from your medication history that you have Bipolar I. Topamax isn't a mood-stabilizer: so that is probably a reason why you shouldn't switch! I'm on Topamax myself, but if you have Bipolar I, Topamax is supposed to be used only as a secondary medication to a primary mood-stalization medication. Topamax itself is an anti-seizure medication. I have Bipolar II "soft" bipolar, so i mostly have depression, and take 3 (count 'em!) anti-depressants, plus the topamax to even out the mini-manic episodes that I have.
I have lost tons of weight from the topamax, but that is no picnic either: I have to force myself to eat because I have no appetite, and have to drink those disgusting protein shakes (bleh).
Maybe you could talk to your doc about adding topamax?