Mirena and sex

So please don't judge. I am 25 and have only been with my boyfriend for 8 years now. I just got mirena after being on the pill for 8 years. I love it. My boyfriend and I have decided that since it's a lot better % against pregnancy to try him finishing inside me. We have done it 3 times but I'm nervous about getting pregnant. Can someone please give me some words of advice or comfort? I feel like an idiot for being so nervous and scared about something like this. I know the % is very low to get pregnant and I know it's possible to still get pregnant. I just don't wanna freak out anymore. I have an appointment to see my doctor about an unrelated item and wasn't sure if it's too early to see if I'm pregnant. Ugh help!