What should I do? To proceed further.

I'm 23 years old and I've had recurring depression for the last 6-7 years. In the last 3 years I've developed severe anxiety and have trouble maintaining relations or going out to meet people. I prefer being alone and don't talk to anyone for varying periods of time. I have sought psychiatric help and therapy many times but I always strop treatment and therapy after 3-4 months. Every time I start treatment I feel immense pressure to get better and that stops me from continuing. I have unpredictable mood swings which last from a few minutes to days at a stretch. I even neglect basic bodily hygiene. I'm unable to achieve my goals because I find it pointless. I'm often suicidal and harm myself by cutting and overdosing on any tablets I can find. I feel that depression alone isn't the problem. I would like an accurate diagnosis and help on how to proceed further.