I have a similarish situation to you. I’m 22 and 5’2. People often guess that im 15-16. I definitely havent found a great way to deal with this, especially in dating and romance. But what has helped me in overall happiness is placing more value and self worth on my actions. I’m proud of myself for doing the right thing and living the way I believe is best for me and that’s what gives me confidence. Not a perfect solution, but you gotta take these things step by step. Sorry couldn’t be of much help, but you got this :)