HCG went up but did not double please help me

Melissa • TTC 3 years. IVF BFP 9/17. 🥚due 5/18

I am panicking. I am two weeks past transfer. Got a HCG Of 109.6 Monday and today it is 143.7. So it's gone up but not doubled. The nurse said it could be fine - maybe both tried to implant and only one took but the other held on but also maybe ectopic or miscarriage.

Pleas tell me this could still be okay. Please