I’m so confused

I’ve been using this app to keep track of my cycle and see which days I am the most fertile. One of the days we had sex I was all the way up to 32% and he came inside of me. I was supposed to get my period back on the 28th/29th, but I haven’t gotten it yet and I have taken 2 tests and they were both negative. I have had a lot of cramps like I’m going to get it and mood swings and dizziness, but still nothing. Anyone know what is going on? I’m so confused.