Any help appreciated

I had what I thought was my period last month but it was a few days early and it was brown but I was able to mostly fill up pads. Then these past few days my nipples have been very sore to the touch and I have had a pain kind of where my right ovary would be, I know I’m in my fertile week so I wasn’t sure if that was why? Also, I had unprotected sex on the 15th and the app says my chances of pregnancy were 8% that day, so low but still something. I was just wondering if there was any possibility I could be pregnant or if I’m just stressing myself out and overthinking things too much. I feel like I started second guessing my period but I have read that implantation bleeding is very light and doesn’t require a pad but I have heard that it can be brown. I bled for 3-4 days and it was enough for me to have a pad for the whole time. Would I be noticing any pregnancy symptoms? I really don’t think I am pregnant but I do know that it’s always a small chance.