4 days late

So I lost 20 pounds and have been having a regular period since January. I was getting them on the exact date the app was predicting, but this month it has yet to come. I’ve been having sore breast, I was cramping if I was going to start my period but never showed and excessive saliva in my mouth 😂 idk if that’s a early pregnancy sign or not because that’s never happened To me before. I took a First response 2 days ago and it was neg. I’m just wonder if it’s maybe my PCOS screwing me over again or if maybe I tested to early. Any thoughts?