Hi Twister,
I'm sorry for your struggles - I can identify with most of them.

Here are a few thoughts - let me know what you think:
- Regarding the chewing on hands, I'd recommend putting something that tastes bad on your hands (vinegar, lotion, etc.) so that when you begin to bite on them you are treated with a negative taste. This may help in conditioning your mind to associate biting your hands with negative rather than positive feelings. I have issues with pulling hair and picking at skin - so I can understand a bit.
- Depression is a nasty one. I know you don't want to take medications - but I would suggest an anti-depressant may be very helpful...they oftentimes help with anxiety and depression...might even help with the dermotillomania. I've taken zoloft, prozac, and wellbutrin. I've found prozac the most helpful for ocd, wellbutrin the most helpful for depression - I currently take both.
- Have you seen a therapist who performs Cognitive-Behavioral Therapy (CBT)? Traditional talk-therapy doesn't work with some forms of anxiety - I think dermatillomania is one of them. I'd see a CBT therapist if you haven't already.
- I've read a really good book by a CBT calling Feeling Good The New Mood Therapy (David Burns), I'd highly recommend it for combatting the depression.
Best Wishes,
Dave