Have I got DPD?

Hi. This post might be a little bit too long. I apologize for it.

I think I might have DPD. The thing is, I don't want to over-analyze and over-diagnose myself with such things. Maybe I'm just sensitive in specific ways. Maybe it's not a bad thing. So, where to start?

I've always struggled with depression, anxiety, and social phobia. Neither of those have been severely damaging to me. On the one hand, I took antidepressants as a child, on the other, I've managed to cope without any pills for my whole adult life. No history of self-damage or suicide attempts, though I've experienced suicide fantasies.

So, why am I thinking about DPD? I've figured my mood changes rapidly depending on how other people treat me. When I don't get a reply to an e-mail, I fall to darkness easily and, on the other hand, getting a positive feedback of any kind can dramatically turn the wheel, so to speak. In my last relationship, I discovered I did a lot of stuff just because my ex wanted it without focusing on what I actually want. I never did anything I felt really uncomfortable about, though. The thing is that as I was sorta passive and accommodating to protect the relationship, it caused the certain opposite.

There were mere causes for the breakup and I've decided to try and get my ex back (which is something I don't consider an unhealthy decision by itself). I try not to push too hard and it seems she does think about getting back with me, too. The thing is I've realized how strongly my mood depends on how she responds to me. Am I feeling really down? It's probably because she hasn't replied for my e-mail for days (she's miles away now, coming back to "my" city in August...). Am I feeling happy? It's probably because I got a nice message from her or she told me something sweet on Skype.

I always thought she was simply difficult to deal with, fluctuating rapidly and so on. Which is true. But, apparently, not the whole truth. Aaaand coming back to childhood, my strong memory is that I depended heavily on my parents. They were (and still are!) very loving but often didn't let me to do things which they thought I wasn't able to accomplish myself. Being a clumsy child, it was often easier for them to do many things for me...

On the other hand, I think I've got strong opinions on many things, I've got an independent moral code, am principled and don't change my opinions and decisions based on what other people tell me (most of the time, that is). I would say that I make decisions about my life myself even though feedback from others is important for me. I find my condition useful in many ways -- I have a strongly developed empathy, for example. I want to try and get training as a psychotherapist because I think I've got potential to be good at it and I feel the need to help people. But I'm afraid it could be dangerous for me and others if I've actually got DPD.

What do you think? Thanks in advance.