Measuring 3 weeks behind

So I know for a fact my last cycle was on 08/29/2020 and I have been tracking my periods on this app since February. I had my first positive test on 09/25/2020 tested a second time with another positive tested again about 3 days letter with another positive. Had my first dr appointment yesterday suppose to be 9weeks and 3 days according to my last cycle but was only measuring 6weeks and 1 day. Assuming they could not detect a heartbeat (they never mentioned it to me). Did some blood work to check my levels. Few hours later they called saying my levels looked good and want me to come in Thursday morning for more blood work and possibly another ultrasound. Anyone else experienced this early on in your pregnancy and had a positive outcome? I’m trying to stay positive but also trying to be realistic and not get my hopes up. Please say a prayer for me and my baby.