What is wrong with me?

My husband and I had sex 15 times in between my last two periods. Multiple sessions sometimes and even caught a peak day during ovulation. And then my period came EARLY of all things. What could I be doing wrong? What could be wrong with him or me?? I know the old saying “it’ll happen when you stop trying” but how do you stop trying?? I’m feeling like I can’t do the one thing a woman’s body is supposed to do! We’ve used the pre-seed for months. Researched all the best positions. I’ve been taking prenatal vitamins since July 2018. I just don’t know anymore