IUD and bf cumming in me

I've had the mirena IUD for 2 years and it's been awesome! But me and my bf just had sex a week ago for the first time and he cummed inside of me. I'm freaking out because I'm not sure if I could still get pregnant or not. Not really ready for another kid right now but if I was, I wouldn't mind it being with him. Just needing some advice please!