I took these tests 9 days ago

According to my LMP I’m supposed to be 5 weeks ... I had an ultrasound done bc I was having some side cramping. The ultrasound tech said she saw nothing but thickening of my endometrium... she didn’t even see a sac,nothing... she said to me .. you’re probably like 3 -4 weeks pregnant right now... how would I have gotten those positives at 2 weeks? Isn’t that impossible..... does anyone know what’s going on or did this happen to you?