Hey there @Fun welcome to the forums. I hope you find it to be a warm and welcoming community. We have some forums Tips & Tricks for newbies if you wanted to have a read through, and please feel free to reach out to the moderation team and the peer support workers if you ever need support.
I think it's great that you have been putting effort towards your mental heath with things like exercise and creative pursuits. Those things are so, so important to maintain - however, we also gotta take the time to do stuff like reflect on and process past traumas and explore our sense of identity and self-talk. Do you have a good therapist to talk to about some of this deeper stuff?
Getting a BPD diagnosis can be super challenging - as you've probably already noticed, it's one of the most misunderstood and stigmatised diagnoses around. A lot of information about BPD online seems to be from the perspective of those observing, not from lived experience. Even from what you've just said, it sounds like you've found info that paints a pretty awful picture. For instance, overreacting and being very sensitive are common for folks with BPD, and it is often the result of growing up in an emotionally unstable environment. Our brains are geared to survival more than anything else, and if you experience a lot of situations that overwhelm your capacity to cope (aka trauma), the survival system can become like a faulty smoke alarm, going off at even the slightest hint of something threating your sense of safety. Hence, having big reactings to seemingly small things.
Even just the phrase 'behavioural problems' really irks me, because it makes it sound like it's an active choice to be... I dunno, 'difficult' or something. But that's not how our brains work. In my experience, and from what we know of how our nervous systems respond to trauma, becoming reactive to certain types of triggering situations means our brains are working exactly as they should, and as they have evolved to react.
Sorry to ramble at you! Some of my closest loved ones have BPD and I know how much they've struggled with the stigma and the type of language that is often used to talk about BPD, which can make one feel pretty crappy.
I think it's also normal to find it difficult to open up to loved ones about the struggles we face. We don't want to burden them or overwhelm them. On the flipside though, none of us deserve to struggle all alone. And I know for myself, if someone I cared about was struggling, I'd much rather they talk to me about it than feel like they have to keep it hidden. Do you think your brother or friends would feel the same?