I’m going insane here. Has anyone had similar experiences?

Because of an irregular cycle we aren’t sure of how far along I am. Went in for an ultrasound for what should have been week 6-8. Found a gestational sac but couldn’t find anything inside. The dr thought that most likely I’m just not as far along as we thought. She sent me to get bloodwork done for hCG. My levels were 44,100 on Friday and 2 days later on Sunday were 53,065. So not doubling but growing. Also seems to me that it’s a pretty high number for someone who “isn’t far along”. I’m going crazy. What gives??? Anyone had similar experience please share!!