Help.?!

Can having sex to young ( I'm almost 16) hurt you future. My mum told me once if you have sex to young you can have problems later when you want kids? I'm not a virgin and I'm in a serious relationship with my boyfriend (we have been together nearly 4 months) I'm not on any birth control but I think I really need to be, I also have heard that birth control can also make problems. I don't want any problems because one day I want heaps of kids. Help anyone!