I feel insecure? And tips?

I'm 15, and I'm extremely shy. My average weight is 115-120lb and I'm 5'3. I have a size of 34B and I feel like I have a stomach that REALLY pops out, though Ive gotten used to sucking it up. I go to an online school, because I was feeling depressed, and I felt like I couldn't talk to people either. There were these guys who would hang out a window of a clroom during the first lunch (but I had to go to cl because I had second lunch) and I was the only person who went that way. They would shout things like "Hey beautiful" and "hey hottie" and whistle, and It embarred me and I think they were making fun of me, because I had no idea who they were. I've only had one relationship, and that was with a guy who was 17. He talked me into ting him and showing my body to him over a period of time (almost every night, or whenever he wanted me to). And then he left me for his ex. He seemed to have an whenever we did that (though I'm still a virgin). I feel really insecure about the way I look. And lately I feel like since I want to be a virgin until i'm married, I won't know how to please or turn on my husband. I'm scared my body will turn him off, and the fact that I won't know how to do things like woman on top or bjs and turning him on. I really want to please him (whoever he is lol I guess I'll have to wait until i'm married to find out who he is) but personally I really don't find pleasure about that unless I know someone likes it and enjoys it. So tips? What do you love to have girls do to you? What turns you on? I guess I'm too young to worry about that stuff but I worry about it all the time? And does it really matter how good a girls body looks?Thank you for taking the time to read this!