I do know what you mean. I can sense other's feelings too. And sometimes I find myself mirroring them and taking them on as my own.
I often don't know what I want. Which is why SLEs are like a breath of fresh air because it feels like they always know. And yet it's important not to let other people define you. I think, for me, it's helpful to take a step back and put some emotional space between me and whoever's affecting me at the moment. Take a break and try not to get lost in who they are. But it's tough.
Reflecting and mirroring comes so naturally to me. I don't know... I mean, I wonder if I've ever known what I want really and truly, apart from others.