Ultrasound two weeks behind lmp?

Sa

I went for an early scan on Monday due to some light spotting. According to my lmp, I should have been 7 weeks. The ultrasound tech told me I was measuring closer to 5 weeks.

She saw the gestational sac but nothing else. If I truly am 5 weeks, that would be a normal scan. Has this happened to anyone else?

My last period started May 13 and I believe I ovulated around May 29-30 according to OPKs.