Well, I can only guess.

But people with bipolar have no triggers that cause their changes, also - they don't necessarily have rejection issues. In my opinion, that part is coming from your BPD. I kind of discounted my BPD, and focused so much on my bipolar, but in learning more and watching myself, I find I am much more regularly effected by my BPD. My bipolar I consider to be the cause of my delusions (like yesterday seeing a ghost, or when I feel like trees are giving me messages), my depression and mania (and what comes with mania). My BPD comes on when triggered, in social situations, in fears wrapped up in emotions, in how I interact etc. It can cause me to obsess, or get delusional in looking at patters, or the radio is choosing songs as a way to indicate the direction I am too take in life.

So, figuring out which is which is an ongoing process - but remembering trigger vs no trigger is a key. Also, BP cannot be cured, its a brain thing, but BPD can be overcome.

So much of our identity is created while the disorder is being created it is hard to tell where we start and the disorder starts.