If it has gotten better since school it might not be AvPD (plus you say you have lots of friends now). Personally I think I used to just be social phobic but became AvPD over time... maybe social phobia is more relevant to your situation, but that's just my take based on your post.

Also depression... I think about killing myself but have never actually been close to going through with it like you so I can definitely relate to that. Just a nice thought to think I have a backup plan, haha.

I think of dying when I am overwhelmed by everything and don't want to deal with any of it so I hide out from it, but when reality starts creeping in I get suicidal ideation. I also don't think I'm "classically depressed" like you say, but most of the time have a constant low-grade depression (occasionally it gets pretty bad but I can still "maintain" to a degree). When I'm depressed it's not like I'm paralyzed in bed and not doing the things I absolutely have to and I don't really cry, but I think it's still depression.

The self-injury is most worrisome I think... that's a sign that you really should go see a psychiatrist or therapist I think (if you aren't already). The "going up and down" you mention makes me think of BPII/cyclothymia, and the self-injury makes me think borderline personality (but that doesn't sound right to me based on your post)... I would say definitely go see a psychiatrist if you can because they can definitely help you more than us and help you understand what it might be - whether it's social anxiety + depression or maybe something more. SSRI's can be really helpful, I think I am about to start taking paxil again. Bottom line, don't listen to my blathering, go see a good psych and good luck! Either way you are welcome to post here. Lots of people here are diagnosed AvPD, but suspect they are because of their avoidant tendencies.