Well, your inability to socialize would be a good place to start. Are you shy? Or do you just prefer to avoid people for some reason? Low self-esteem (I have this a lot)? My shrink tells me my depresssion is a chemical imbalance. I have had times though when life has thrown me a few curves, we all do. Most of the time I don't have a reason for the depression, it's just there. I took Effexor on/off for 7 years. I would gain 60lbs. each time I was on it.....lose it when I stopped. I am now on Wellbutrin, but lately, I think I need more as I am going through perimenopause (pre-menopause), which causes a lot of sobbing for no apparent reason.
I resisted going to a shrink for a long time as I felt I didn't have anything to say. Finally, depression got so bad I didn't have a choice. You will find the words to say and hopeully, therapy and maybe a med will get you back on track.
Let us know how the first visit goes!