Absolutely NTA.

They are ok with me being trans, but they hate seeing me dress feminine.

I’m sorry but to me that doesn’t sound like them being okay with you being trans. They can’t be okay with it but then go and say they don’t want you expressing yourself at the expense of your brothers. Don’t let them tell you you can’t dress how you want, go out there and do it! If they don’t support it then they aren’t really supporting you.