How far along am I!?

Help me out here. I had a chemical pregnancy that ended on it’s own the weekend of 11/12. I took a test the day after Christmas, thinking it would be negative, and it was a BFP. I’m counting my miscarriage bleeding as my “last period”, so I’m thinking that I’m 6 weeks. I’m going in next week for an early ultrasound. I went in yesterday for a blood test and my HCG is 91,000!! I feel like that’s so high for 6 weeks. Please don’t tell me this could be twins 😅 the chart my doctor provided said that 91,000 falls within 6 week range but all other charts we find online indicate that 91,000 is much further along. Did anyone else have very high HCG? I never had my HCG tested with my son and it never got above 275 at 6 weeks with my chemical. Feeling so so grateful and excited but confused !