It sounds as if your mom has her own mental health problems. One in which one of the symptoms is a lack of self-identity and therefore she will look to others to define it for her. There are a few like this, one that I deal with is BPD but she may deal with something else. No matter what it is though, it is not your responsibility to take care of her and that is what you end up doing by allowing her to use you to identify her self image. If your mom is not already seeing a therapist, I would suggest you lovingly recommend it to her. You, should focus on you and your life. It's only by doing that both of you will perhaps be able to lead happy and healthy lives. No matter how happy your mom may claim she is, it is hard to live through someone else, and never truly satisfying, therefore she can never be truly happy. You, will never be truly happy trying to do things you believe will cause her to feel happiness. Both of you will only have a chance at true happiness when you both have your own lives. Love each other, spend time with each other, but be your own person.

This was a hard lesson for me to learn. I resented it when people I was close to started doing this at first, but I have come to understand we all needed it and how much we all needed it. So, your relationship with your mom may get strained at first, be prepared. May even be strained for a few years, but in the end - you will find you are happier and that's what matters.

Good luck!