It's really a difficult topic. Things you might want to think about is how culturally accepted non traditional roles are in your culture and maybe reflect how that influences the gender you are aiming for. As you said you are looking for a person your age, they are also still finding orientation in their sexuality.

So maybe the girls you mentioned aren't opposed to be in a more dominant role but never considered it due to the Expectations that are set? In the end it's up to the individual, so you will have to get to know people to find one. Kinky dating apps could be an option, but also standard ones.

If you live in an area that is a tad more open or close to a bigger city there's a good chance they will have bdsm meet up groups. At least in my vicinity they also have a special group for people between 18 and 25, so maybe try your luck there?