Okay so my therapist of two years suspects I rather have DPD than BPD, after I told them about recent episodes I experienced. He says my self-destructive behaviour is not intensive enough, as I form functioning relationships with people, contrary to a classic BPD where you would naturally act-out on your emotions and experience a lot of anger. However it seems there is also this not classical term of a quiet BPD which strongly correlates with what I'm going through. 

On the other hand, my therapist suspects DPD (or some other emotional dependance thing). The diagnosis explains a lot of the symptoms just as BPD, and would also partially explain why I do not experience a lot of anger. However, I have a few concerns. Firstly, I do not think of myself as indecisive. I also tend not to rely on other people, and in fact are quite superficial in relationships with friends and family other than my girlfriend, whom I thought was my FP. With her it's quite the opposite. Second of all, I do experience splitting. One week of devaluing my GF, one week idealizing her. I learned these are two sides of the same coin - fear of abandonment, which is what my therapist agrees with. 

He generally says I'm more like DPD but have the defence mechanism of splitting. But I am not sure about the diagnosis, and it doesn't resonate with my feelings all that well as BPD. But I suppose I should trust my therapist like I would trust a doctor, since they're supposed to know better... however 2 years into the therapy, I still believe to be roughly the same person I was before, and I don't think the therapists' skills helped me all that much after all this time (definitely more than 80 sessions). 

Should I double check with some other councellor? Did you also face a DPD diagnosis as a possibility? What's the difference between a quiet BPD and DPD?