I think there is a balance that we can reach. Rather than fixing somebody's problems for them, you can listen, and then say, "What do you think you should do?" I have tried that with my AM and RABF lately, and it seems to work. They seem to respond well, and it keeps me out of giving them advice. I want to keep my empathy for people, without getting involved in their situation. It's one thing to say to someone, "I'm sorry you are going through this." It is another thing, if I am thinking about their problem when I'm at home and need to be taking care of myself.
It sounds like you have a real gift in terms of being someone who people want to talk to. It sounds like you need to set some boundaries as to how much you will allow people to "dump" on you. Also, work on saying, "What do you think you should do."
Also, if these are not two-way relationships, then maybe you should spend less time with them? I know they go to you with their problems, but do they listen when you have a problem?
My opinion is that you don't have to completely give up who you were to become the person you want to be.