Should I worry

So initially going off of my period I was 6weeks, but my cycle isn’t regular it has gone up to 38 days recently. So I had my appointment today for an annual visit but they also did a ultrasound to confirm pregnancy. All the Doctor saw was the gestational sac so he thinks I’m around 4 weeks. It makes sense I guess because if I had a 38 day cycle I would be around almost 5 weeks. I’m trying not to worry and panic but I can’t help it. Somehow I’m 2 weeks earlier than I thought or nothing is going to develop.

This also means I tested at 4 weeks pregnant and got a positive.