Ladies! I need help. I'm super worried.

So I had my IUD put in in the beginning of December. I had one period after that in January that only lasted 4 days. Then nothing all of February until this week I started bleeding.

This app says I'm supposed to get my period in 2 days so it totally could just be it but it's weird that I missed a month.

I've also had unprotected sex twice last month and I know the IUD is supposed to be pretty effective but I'm still worried.

Please share your IUD experiences with me. Is this normal?