Why can't i fall asleep till late like 12-1am ish lately?

so i go to bed around 10:30pm or 11 or something and i'm trying to go to sleep all different ways. I just sit in the dark for a while but then at like 1am i finally fall asleep! but when i get up in the morning i feel like crap because i didn't get a good nights sleep!!! this has been happening for about 3 or 4 nights i can't take it anymore!!!!!! and i'm 12.5 btw. help!