HcG levels

Hi everyone. I’m curious if any of you have experience with HcG levels going up quickly, and whether or not you had multiples. I got my blood test results today and the HcG beyond doubled. I took Femara (Letrozole) and did <a href="https://glowing.com/glow-fertility-program">IUI</a> at CD 13. Here have been my levels so far:

5dpo 0

7dpo 0

9dpo 2

11 dpo 16

Thoughts???