The worst part is that they constantly want my help and when I try to honestly help, even in ways sensitive to their own fragile thought process, I immediately get stopped, talked over, or hear a “yeah, but”.
They want my help, but the reality is they want validation of the very things they claim to want to try to get over.
Think about it this way. If I say to you, "Help me lose weight," there's many ways you can respond. And I think the only way you give an appropriate answer is to think about, "Why's he asking the question to begin with?"
When you're asked for help, your BPD is looking for understanding first and foremost. And you should be able to give that since you know what it's like to feel frustrated or stressed.
And I get it, focusing on "feelings" doesn't actually solve the problem. It makes them feel better in the moment. But what if the actual problem, why they're ranting on and on about their terrible life, is the perspective they have from their feelings?
Then you can give a great bit of help just listening and showing compassion.
It's very easy to want to fix someone else's problems by telling them everything they're doing wrong. Even without the mental illness aspect, what we say can do more harm than good if we're not careful with our words and intentions. And I'm not saying that you're doing that, but try to keep that in perspective anyway. Dealing with BPD is a marathon, not a sprint.