Hello dear,
I understand your concern.
In my opinion the December 1 st might be considered as your last menstrual period (LMP).
Usually the age of
pregnancy need to be calculated basing on the LMP.
For it the last 3 menstrual cycles should be regular.
But as you had
miscarriage last time and bleeding was prolonged
ultrasound might be helpful.
Ultrasound taken within 1 st trimester ie.,within 12 weeks of pregnancy helps in accurate estimation of age of pregnancy,the well being of conceptus and also for the accurate dating of pregnancy.
So I suggest you to go for ultrasound.
And also rule out any thyroid abnormalities,
progesterone insufficiency,any genetic anamolies etc which are the causes of first trimester miscarriage.
Nothing to worry.Relax.Take healthy nutritional diet and
folic acid supplements.
Avoid physical strain and intercourse.
Hope this helps.
Best regards...Dr.Srilatha