Cant get pregnant....

So I ad my first son back in 2015 no problems, healthy, born at 42 weeks via C-section. Had a mierana birth control put in at 6 week check up(took antibiotics medicine about a week before it was inserted because of C-section) I had the birth control in for 3 years. Once I had it removed we have tried and tried to have a baby but ended with 2 miscarriages and nothing else sticking. Do you think the birth control could have caused this? My obgyn said no but would not check into the reason on why this is happening. I'm hoping I'm still fertal. Any advice please?