Hcg increasing, but slowing down

Looking to see if anyone has gone thru something similar. Hcg initially doubled in less than a day. This last test doubled after about 3.5 days. Worried it didn’t increase more. Had an ectopic in November so monitoring closely. No bleeding or cramping. The doctor said she’s not worried since it’s still so early. Getting another level in 48 hours. Thanks in advance for your input! Feeling very nervous!

10 DPO- hcg 32.2 progesterone 20

12 DPO- hcg 128 progesterone 26

16 DPO- hcg 268.3