Hcg not doubling

Shelby • TTC #1 🌈

Just need some opinions of other with similar stories and or success with low hcg

Initial hcg 14 dpo 33

16 dpo 76

18 dpo 87

21 dpo 192

My labs seem to be doubling every 72 instead of 48. Please let me know if anyone has any similar situations.