I don't know how far along I am

Taunie • Pregnant with my 2nd

I have an ultrasound on the 23rd to see how far along I actually am, but it's killing me not knowing. My last period was technically December 6th, but I had an ultrasound February 13th and they couldn't see anything. My levels did increase from 370 to 917 in 2 days so I'm trying to be hopeful. I've just been so concerned because of my previous miscarriages.