@spidersam as a short dude who trains, and hears comments like those a lot, 2 pieces of advice. First: You can't change your height, so why does it matter? If they make comments about your frame, you can change that if it really bothers you, it will just be a lot of effort. Second: It sounds like you could learn some better communication skills, learning to set boundaries and asserting yourself. There's a lot you can research on how to do that (pm me if you want more info), but here's a basic webpage on communication styles that could help you get started.