PLEASE HELP ME

I'm really young and trying to get preganant, my boyfriend and I have tried everything. We experienced a miss carriage 2 years ago and we have been trying since January. We have sex often and I try to eat healthier. I'm also very active with summer volleyball and track and I do college cheerleading and coach. I'm rarely ever stressed but it saddens me that I can't get prgnant. I have seen my don't it and I'm fertile as my boyfriend is as well. And I was told I'm in good health. I know my ovulation days and take tests all the time but I still can not get pregnant! It's been 6 months. PLEASE. PLEASE HELP ME.