HCG levels high?

Momma's, on August 13th at only 4 weeks 5 days I had blood drawn my levels came back at a 16,446. On August 15th at exactly 5 weeks I had blood drawn again and it came back at 23,872. Is this abnormally high for that early on? Ultrasound at 5 weeks confirmed I wasn't any further along than 5 weeks but the only thing I think I saw was a sac the ultrasound tech only did an abdominal ultrasound and didn't zoom in on the sac. I go to the doctor tomorrow to make sure everything is okay and normal I should be 8 weeks 2 days. These past 3 weeks have been nerve wracking and I'm so scared.