I think I might be?

So my boyfriend and I have been having sex for about a year, and he always "releases" inside me. Now, we've always done this. But when I went to start my April birth control I didn't because I thought I was having bad symptoms from it. I had sec on Thursday when this app said my chance was like 27% or something , this was like three weeks ago. I haven't been late for a period, ever. And now it's Monday and I was due Friday!! I have taken like 12 pt and all negative. I have thick discharge, back pain, and I'm not getting my normal period face break outs. I'm confused. Is this just because I'm off the pill? Could I be pregnant?