I understand where you're coming from and have dealt with the same thing all my life. Idk what happened, but something just clicked in me when I've finally got tired of always wanting to please everyone and rarely myself because I know that I was hurting and yet I was so selfless. I've always put people before my feelings and now it's something I only do when I know I don't need to pay attention to myself.
Don't pay attention to your anxiety. That's all it is, a feeling that wants your attention and with an anxiety there's a very high chance that there's nothing to worry about. If you need to focus on yourself-- your well-being and happiness, do it because you can't make people happy if you're not your 100%.
ALSO, be aware that you cannot make everybody happy. Convince yourself that you cannot do that. If you don't like something, if you don't feel well, if you don't want something, if you do want/need something, you do what you know is right, not what you think is right. If anyone tries to guilt trip you, call them out on it and say it's not going to work this time.
I think doing this has something to do with being more assertive and less passive. I've become a very passive-aggressive person over time because of this experience and you can too. You are important and they know you're important. If they didn't think you were they likely wouldn't tell or ask you to do anything for them. if you feel you don't have a life or identity, build one for yourself and this can be the start of it. Don't let people step on you, but don't be too selfish.
I wish you well.