Depression/Alienation...Loss of Self and Connection with the World?

Hey so i'v been in this confusing situatuon for about 2 years...It would seem that everyone but me is changing...All my frineds are out partying, getting laid, have jobs, going to college this summer, and basically progressing in and living life while im stuck at a stand still. See I feel like I have become estranged and alienated from everyone. I am currently being treated for depression and have had extreme anxiety (depersonalization/derealization,panic attacks) in the past. Currently my relationships with people are poor and feel plain awkward. Every interaction feels like a struggle to get through and the connection is just not there. Hell my SELF isn't even there it feels like. I feel so weak and awkward in public and even with my close friends. Its like Im breathing yet not truely alive...Im a sleepwalker or a zombie or something. No matter how hard I try nothing seems to flow and work out. I always feel like im being victimized and cant stand up for myself. My sense of reality and self are twisted. Its like im missing parts of myself and without them i just cannot function at full potential and strength. It also doesnt help when I see my friends having fun and doing bigger and better things with their time while im sitting in my head alone. Things like partying, girls, and just being a teenager seems so distant. My self esteem has diminshed because of this and i feel terrible. The worst part is that I know when im not depressed i am a wise strong person. I am more then capable of keeping up and going beyond my friends limitations and potential. Plus everyone treats me like im inferior or weaker in some way even though they are just messing with me , it really hurts sometimes and it definatley doesnt help at all. I feel like im a stupid freshman that doesnt know to act better or mature. Though I know that i am a genuine, matured person with real individuality and power, but all of that is blocked by the depression i beleive. And the comments and jokes about me just reinforce the thought that im weak or ignorant or a queer. For now im an outsider...No matter what i do I just cant seem to break this illusion thats keeping me from the ones I care about and keeping me caged in my mind. I am only 18 but i feel like my life is slipping right through my fingers. Everyhting is going through: school, friends, family, self esteem, self image, sanity perhaps? Is this just the depression or have i really become a dead beat? Any insight, advice, or experinces with stuff like this is much appreciated. Just for the record im not some whinny ***** either, Im a straight guy who isnt a coward or rude or immature, stupid, watever. But its just... once everything you had is taken from you and your left with nothing in a cold dark hole, what can you do? Where do you go?