I have no issues at all being described as a feminist. (I certainly don't think feminism is about 'destroying gender differences', although some feminists might be about that) - but I chose to be 'Ms' before I understood what feminism really was, and I wouldn't have allied myself with it at that stage.
About gender differences. What I understand gender to mean is a set of socially-dictated stereotypes, conventions and mores attached to a commonly-shared set of perspectives about what it means to be masculine or feminine. That's a very different thing from male or female. 'Gender' is hard to define because in some ways it's nebulous . It's very definitely ephemeral, because these stereotypes are historically specific, geographically and culturally distinct, and shift in accordance with time and place.
Historically, the central job feminism has done is to challenge these stereotypes and insist they don't tie us biologically to our bodies. In any case, gender is an arbitrary distinction and often has nothing to do with our sexed bodies whatsoever.
The distinction between Ms, Miss and Mrs is one such meaningless convention. They are all truncations of the same word of 'mistress'. I'd be fine with Mrs as a default title for all adult women. As an indicator of sexual status (yes it is, as much as that repulsive term of 'maiden' name 🤮) I'll continue to reject it.
If women continue to insist upon these distinctions then their individual choices are of no consequence: they don't affect my life one iota. I shan't criticise their choice: by the same token I don't owe other women 'support' for their choices on the basis of shared XX chromosomes.
But as a PP upthread points out, it's rude as hell to insist to women that our brothers' names are theirs by right but ours 'belong' to our fathers.
No, they don't. They are ours.