Interestingly I felt similar when I decided to change my name on marriage. It was most odd. At first, I considered whether to do it, and decided to based on (what I still think are) reasons unrelated to sexism, so I felt like this was fine, I had my reasons to do it and I was totally happy with the decision.
Then I did it, and it jarred, and I felt a pull, and now I feel like I'm not allowed to be upset/annoyed that I made the decision to change because I made the decision for totally feminist friendly reasons. Which is bonkers! I mean, what does that even mean? A couple of years on I've finally got around to changing my name on most official things but not all, and it does fit with what I want, but I'm not going to forget my old name and as my childhood best friend says, "You'll always be XXXX to me!" which I like :)
I don't think that you staying in a relationship traps other women in a relationship they are unhappy in. If you went around insisting everyone do the same because look I'm doing it and it's working out so amazingly for me, then that would be different, but I don't get that impression at all.
I also wanted to say that it's okay to feel crappy about a decision you have made. Or not. And just generally to divorce how you feel about it from how "feminist" it is. And also that if you don't want to leave, then don't! As long as you aren't endangering any children by staying, anyway.
In my experience people who are truly unhappy in relationships and don't feel as though they have to stay don't stay for very long. The people who stay just don't see leaving as a proper option for whatever reason.