So confused about my period

My periods are very regular & have been for the last year. Me & my husband had unprotected sex on the days of my ovulation, I use the flo app to track but I also had the signs like sticky discharge etc. Well, my period was due 3 days ago. I took a test on Sunday so The day before my period was due. Took one yesterday and again today (wasn’t my first wee of the day was in the middle of the day) all tests were negative, I even used the clear blue digital one.

I wouldn’t say I’ve had pregnancy symptoms but I’ve felt very under the weather, have swollen gums and occasional nausea apart from that nothing. I usually get cramps before my period is due but nothing. My question is has anyone tested even after their period was due had a negative test but was actually pregnant & eventually got a positive test? I’m just so confused I know other factors can affect my period, but considering I’m always very regular and we had sex on my ovulation days it could also be pregnancy.

Any advise would be very appreciated x