Beta level 11 dpo

I went in for early ultrasound today (4 weeks) and of course they couldn’t see anything yet because it’s too early, but Dr really wants to rule out ectopic as I’ve already lost L tube due to same.

The ultrasound tech told me that 4 days ago (I would have been about 11 dpo) my beta was 20 and it’s takes a higher beta to see anything.

Is 20 low for 3 weeks 4 days or 11 dpo??

My tests appear to be getting darker.

Bottom: 02/21/20

Middle: 02/22/20

Top: 02/25/20