Could I be pregnant ?

I had unprotected sex with an oops 3 days after ovulation, my “app tracked “ on 5/18.

Took plan b 24 hours after 5/19, come to find out plan b doesn’t work after ovulation??

Exactly 7 days after we had sex I had gnarly lower back cramps, I’m suppose to get my period (today) nothing so far. I’ve had nausea a little at night last few nights, and then Last night I had cramping/ stabbing pain in my right lower stomach/ pelvic area. My boobs are so so soar and huge and my nipples are constantly hard and soar.

What are the chances plan b did not work and am in fact pregnant?? I took a test today because my symptoms are too close to last pregnancy but it was negative this morning.

is it too early for a positive if unprotected sex was 10 days ago now?

For reference I normally only ever cramps the day my period starts and I am pretty regular.