I was diagnosed with it. I have a hard time accepting that, but I can tell you this - what helps me most is education. Find some books about it, familiarize yourself with it. Start with the DSM-IV; read the diagnosis and description. Write out what you identify with in the description - learn to separate yourself from the disorder, because you are NOT your illness. When you can recognize your symptoms in everyday life, it's easier to step back and try to "re-evaluate" your situation and reactions.
If you're anything like me - which, if you have BPD, you just may be
- I do not manipulate people as is commonly seen with BPD. Instead I get incredibly emotionally attached to them way too quickly. When I realize I'm latching on too strongly at first to someone, I force myself to step back and take a breather. Intense patterns of unstable relationships with others is a common trait for people with BPD.
It's hard to not be able to trust your own mind. No matter the age, you never truly feel "concrete" in your sense of self and your sense of value. Teenagers go through identity exploration, and it's an expected stage, but for us....it's like you never grow out of it. You never "find" yourself, so to speak. You feel empty. Flat. Incomplete. Then there are times you feel like an emotional rollercoaster - it's not like bipolar-esque mania/depression cycles, it's just that you FEEL so INTENSELY. The depression, the hopelessness, that intense "gray" area. You can't really identify it. You feel like you could just go berserk if you don't lock yourself in your room, away from everyone and everything.
You often fantasize about suicide - this is common, too. You may or may not act on it, or you may turn to self-injurious behavior to get those thoughts out of your brain. It's scary.
Have I touched on anything close to you yet?
I know I don't know you personally, but as someone who "gets it," know that you are always welcome to talk to me.