So heart broken...

So as some of you may know, I was 4 days late on my period. I've never been that late before, me and my SO was getting so excited. But of course, I started last night.. I cried like a baby, and he was definitely disappointed.. I don't understand, I've been pregnant before even though I had a MC, so I know I can have kids. It's just so aggravating to know that you DTD on your ovulating days, yet every month that you do, AF always comes to ruin things! I'm definitely going to invest in some ovulation tests.. Any other tips or advice would be greatly appreciated!!