I've already posted this in another thread but I feel like i need to reiterate the dangers of self-diagnoses and people diagnosing each other online. You need a professional diagnosis, not only because that's the only legit way, but also because the recovery of those with BPD can be significantly aided by medication such as mood stabilisers. You're going to have to go to a psychiatrist eventually, so you might as well do it now and get a proper diagnosis from someone who has been to med school and is actually trained.
Sorry if that all sounds hostile - it isn't meant to be, I'm just worried about the level of misinformation flying around on the Internet in general about BPD. I know it confused me a LOT when I was still figuring things out and I was pulled in all directions. Don't torture yourself - see a professional for diagnosis, and use this sub-forum for additional support. And to everyone who is struggling with BPD, hang in there.
edit: a psychiatrist may also be able to point you to a therapist who specialises in dialectical behaviour therapy (DBT) which is the most effective therapy for BPD, so there's another reason to aim for a professional diagnosis.