Pregnant?

Due my period in a few days yet been having lower belly cramps for about 3/4 days now. Nauseous today.

Had unprotected sex September 17th . 3 weeks ago

And September 28th. 1 1/2 weeks ago.

I feel like if I am pregnant then it would be from the 3 weeks ago mark but it’s not coming up on a test.

Would I be getting symptoms but no positive test? Any other girls had these constant cramps/tight feeling on lower belly a week before period. (Also I normally get cramps 2 days tops before a period never a week)