Do I need anti-depressants? Weight problem..too skinny :(?

For your situation I would consult a psychiatrist. An antidepressant like zoloft could help you deal with some of the issues, but counseling is crucial for you if you want to overcome social phobias/body image issues. Also, SSRIs like zoloft, prozac, etc can often cause slight to moderate weight gain in some people so for you this could be an added benefit. Don't take a SSRI simply to gain weight, take it if you really need it for your issues, but this potential side effect could also be beneficial