M.,
Was a combo of Zoloft with a Wellbutrin augmentation discussed? You may want to ask (and be sure to ask if this would work w/ your current Rx Adderall) since using an add on such as Wellbutrin can boost the effect of the primary A/D which would be the Zoloft.
As far as maintaining weight...have you tried a nutritional supplement in addition to anything you can manage to eat? Adding Boost or Ensure to your daily meals will get in some more calories and nutrition. You can sip them throughout the day...they are pretty good.
Keep us posted so we can keep you in support!
S.C.