Nope. This is where you're missing a beat on feminism.
You don't owe anyone any explanations about things that are not any of their business. Even your friends.
No one else's needlessly scrutinizing opinions are worthy of taking up space in your head.
In the grand scheme of things, your skirt does not matter. It's not important.
No one can make you feel inferior without your consent. Feminist strengthens your spine so that you stop giving that consent.
Why are you wearing that skirt?
"Because I felt like it."
Just shrug.
"Why do you ask?"
"What difference does it make?"
"Because I like it and I think it's appropriate."
"What's it to you?"
This was the point of "bra burning" btw. Die hard feminists will not be giving up that "bra burning" anytime soon. And our daughters will learn from the start not to let the all seeing scrutinous eye erode their self esteem and dictate terms for how to be a woman to them.
We are women. Women are not what they wear.