I agree with the warning issued by Metaphor and Rebe about diagnosing yourself. It's dangerous. But the biggest reason it's dangerous isn't because you'll be inaccurate. It's because disorders aren't actual THINGS. The correct way to think about disorders, imo, is as a set of cognitive/affective/behavioral patterns, and patterns are nothing but reliable cause and effect relationships. If you can really remember this, then you can investigate all you want because they're no real danger of confusion. If you see patterns you like/dislike, you can figure out the cause and address it as best you can. (That's something that'll improve as your understanding of yourself improves.)
The danger is when people make diagnoses into THINGS. They treat them like objects or viruses that you can get, and then they think they have this thing called BPD disorder. It's not that they don't have the symptoms (meaning, the patterns); it's that that's ALL they have. When they believe they have a disorder, then they get confused. I would be confused too. Uprooting something abstract like a disorder is trickier than uprooting a set of cognitive-behavioral patterns. The patterns are there. You can touch them and feel them. The disorder is only an abstraction.
The other problem is that when you find a disorder and start reading about it, you can easily convince yourself you have symptoms that you don't actually have, in order to remain consistent with the diagnosis. That leads to lots of confusion.
In sum, look at yourself. Look and see what patterns are already there, and address those. Don't bother trying to diagnose yourself because it's a waste of time.