To answer your last question, you wouldn’t believe it, but Hasidic/Orthodox people get Jewish clothing… at a store. (Oh!)
But I’d like to address your first statement, now that you’ve shared it with us. If it is in fact true that your mother is unquestionably Jewish, then you follow, you’re a Jew. And being enrolled in public high school not in a Yeshiva is NOT going to get you closer to Judaism. Neither a Yiddish theater company. But those are your own personal decisions. Not for me to judge.
One more thing, focusing on clothing is by no way a step anywhere, unless it’s a girl/woman doing away with untznius apparel. Anyone can sense an actor. Dressing as a ‘Hasidic/Orthodox people’ will in no way make you one, it may in fact distance you from the very direction you want to go. It’s a mistake many newcomers and welcome backers make, they dress like someone from a different lifestyle, and to the world at large only appear as an actor. It’s my personal opinion that the clothing should fit the person, not vice-versa. Again, it’s my own opinion. And I’m not judging you the very least bit.