much earlier than expected, who else had this?

I had an ultrasound yesterday because I was so worried about how far along I was. I was curious, so I had both an external and internal scan. They found a gestational sac, a yolk sac, and a very tiny embryo (just a dot). Honestly, I think I'm much further along than the VK calculated. My last period was September 19th, and I hadn't really had a proper cycle yet since I'd only been off the pill for 3 months. So I feel like I'm only 4-5 weeks pregnant. Last Thursday I took a Clearblue test, and it said 2-3 weeks, so that could match up, right? I'm having another ultrasound on Friday, but I'm keeping my hopes up.

My question is: who else has experienced this?