HCG levels not matching up?

Breanne
Hi everyone, this is my first pregnancy and I'm not too sure about hcg levels other than what I've googled. 
Dr called me this morning saying my hcg levels are at 46,000 at about 6 weeks.. but my boyfriend was away and returned Jan 16th so I wouldn't have conceived until after then?! My periods are very irregular (5-6 weeks) so I'm just not sure! Very confused. 
I have 2 separate ultrasounds tomorrow as they think I might have an ectopic pregnancy or gallbladder stones 😞