HCG results after FET not doubling

Hello all, I had my 5th transfer with a frozen embryo on Dec 2nd. My HCG leves worry me. Do you have any experience, positive outcomes with HCG levels not doubling in the beginning? On Dec 10th HCG was 95, on 12th of Dec 161 and tiday on the 14th of Dec HCG was 227. My dr said not to worry, it is ok as it is rising and also that I do not have to test again unless I have spotting or cramping and schedule an ultrasound, but they will let me know when just next week. I have a history of missed miscarriages and ectopic pregancy so I was surprised they said not to test again. I will test the HCG level again of course as I am really anxious...do you from your experience think this might be ok? I also had some spotting 2 days ago but it stopped.