Frustrated..

I just don’t understand why it’s so hard to get preggo! I keep doing everything right by BDing it before, during and after my ovulation! And every month, I still get my period! I got pregnant December 2018 but unfortunately, it ended in a MC in February! I was also told that you are very fertile the next 6 months after MC but I still feel like I’m having a hard time! What am I doing wrong? 😢😥🥵