Nothing seems to be happening!!

Been off the pill now for nearly 7 months I'm 22, and have frequent sex especially in my ovulating period, but still nothing- I no it's still early days yet for someone my age trying but annoys me when my friends aren't even trying and still smoking etc and getting caught! I feel bad for feeling this way. I take my vitamins and do exercise. Stopped smoking now for 6 months and I hardly drink now. Any tips or advise?