First of all, the guys may know you’re only 15, which they may think is a little young for them. Although you’re mature, there’s often a big difference in life experience between some 15 year olds and some 17 and 18 year olds, so while they like you, they’re nervous getting involved with someone your age.
The other thing is that some guys who are 15, 16, 17 and 18 — may have adult bodies and more years on the planet than you do, but they’re not mature enough to ask you out the way you may expect them to. Teenage boys are still on a learning curve when it comes to dating, so you have to go easy on them by way of your expectations.
I hope that helps! 🙂