Hello, I've Been On The Mirena Roughly Since Last May.

Hello, I've been on the mirena roughly since last May. I've had cramping here and there but when I first got it, it was dreadful and unbearable! Finally it subsided however here are my concerns. Every time (almost all the time) we have sex it feels so painful when he goes in deep that we have to stop. Not only that but when we're done I start cramping and goes on for a couple days. We are both agree to let him ejaculate in me, so could I be pregnant? ( I haven't had any period since I got on the mirena) What's wrong with me?