Late period HELP

I had unprotected sex but my boyfriend pulled out. I have a very irregular period so I pretty much always have it. I was on the pill to regulate it and act as birth control but I stopped to get my period because I’m getting a IUD. I haven’t gotten my period in over a month and my cycle started 3 days ago. I took a pregnancy test last week and it said not pregnant. But my period is late and I never experienced not having my period for this long. Should I tell my mom she keeps asking if I have gotten it since I’m supposed to get my IUD Monday. Am I pregnant, should I take another test, should I tell my mom, thoughts?