To be able to help you better, I would like to know the following details:
What was the date of your last menstrual period?
Was a first trimester ultrasound
done? If yes, can be tell me the date of the ultrasound and the period of gestation in the report at that time?
Did you have regular menstrual cycles earlier? If yes, what was the duration of the cycle?
I'll be to help you better once I have the details.