I'm 15 and NEVER been in a relationship?

Is this normal? My friends and parents and a couple others say that i'm pretty, but i have a hard time believing them because the only boys that have ever asked me out are 3 (trying not to be mean, because they r kinda friends with me) not the best lookin/actin kids around...... so therefore i said no, but i have never been in a relationship :( never found someone that liked me that i like back :( and it makes me sad, is this normal? and is there a time, where i will "bloom" a little more (get prettier/taller/more attractive) my mom said it happened to her at 16/17 but honestly i don't think i will change, and i don't think boys will like me cause they don't now :(