Gestational sac?

Cl

My last period started around the 9th of December and I haven’t had any bleeding or spotting since. Been having cramps for two weeks. Negative test just over a week ago and last night very positive tests! Went to the er as I was a bit shocked and worried about cramps and the test was positive there too.

So today I had a scan all that was visible was a 2 millimetre growth that they think is the start of a sac and a little cyst on my ovary. Shouldn’t I be 6 weeks I don’t understand how I can be so early on when my last period was so long ago

I’ve not to go back for two weeks so am very anxious

Any replies would be very helpful !!