Why can't I get pregnant again?? 😭😭😭

My husband and I have 2 children ready and have been trying for a 3rd. We got pregnant so quickly with them (within in days of trying). But this time we're not having any luck! I had my Mirena removed on August 2nd. I've taken ovulation tests, but none of them have said I'm ovulating! I've had regular periods. I know it's only been a few months and there are many women who have tried for years! I am just heartbroken bc it hasn't happened.