28yo fem w/ depression, anxiety. Zoloft for ~10 yrs, 50mg then 75. Added welbutrin. Zoloft quit helping, tried lexapro (escitalopram). Big weight gain. Rec new drug?

Antidepressants best. Another antidepressant, possibly snri like Effexor (venlafaxine) may be more helpful at this time. Add ons such as gaba- calm and natural anxiety aids can help. They do cause weight gain usually. Therapy is always an important treatment modality for depression and anxiety, don't think it is not helpful!
See ur psychiatrist. Your zoloft dose is modest. Have you tried increasing the dose before adding wellbutrin (bupropion)? What are the doses of wellbutrin (bupropion) and lexapro? If you are concerned about weight gain and if wellbutrin (bupropion) works, ditch zoloft and Lexapro but the dose of wellbutrin (bupropion) has to be adequate for it to work. Discuss this with your psychiatrist.