I feel like I’m pregnant

I’ve had my mirena for a year and an half. About a month ago my boyfriend came inside me for the first time (sorry a little tmi)

Since I got my iud I’ve still had periods, really light. But it’s been a month and still nothing, no blood. I did get severe cramping two nights ago out of no where.

The past few weeks I have been feeling so shitty. I’ve been super fucking nauseous and very dizzy. I been literally eating anything that I can get my hands on and I can barely pull myself off the toilet because I poop like 3 times per hour.

I’m so afraid that I’m pregnant. But I can’t go off of me not having a period because what if my iud has decided to not give me periods anymore.

I’m really thinking of buying a pregnancy test but I don’t want to get an expensive one. Where can I get those really cheap ones that come in a big pack?

I’m so confused. Help