I cant make up my mind?

i don't know what to do! i really want to have sex im like so horney iv been thinking about it for a long time now and i dont know why! its not like i dont have anyone i have been talking to this boy for 2 years and he want to do it too and idk what to do i want to but i think my life will change, are my mom will find out are have a baby! i want to stay pure but i want to do it this is so hard for me i want to know how it feels i just want to but dont know why im asking are idk i need someone to talk to please help im 15 and so is he!