I understand your concern. 120lbs.... Wow, I'm sure that did take alot of work!
Have you been exercising regularly to achieve your weight loss? Regular exercise sometimes helps with depression and anxiety.
My other thought is that you could talk with your doctor about your concerns. There may be medications that would help you that don't carry a risk of weight gain. The reason I keep bringing it up is that severe anxiety and depression are absolutely no fun and can be really debilitating affecting your ability to function as well as your quality of life.
Check out this article:
http://www.ccjm.org/pdffiles/Deshmuhk703.pdf On the second page (page 616) there is a chart that shows at least two kinds of antidepressants that don't pose a risk of weight gain. I, of course, don't know if they would be appropriate for you specifically, but it might be worth having a conversation about it with your MD.
Take good care,
FT