I am confused. Did my pregnancy started from the first day of my last periods, is it possible?
Yes you are right, your pregnancy never starts from periods. It mostly starts from day 14 of periods when egg normally releases from ovary to fertilize the sperm.
Then why doctor calculates pregnancy from first day of last period. That is because of convenience because women all over the world remember their period date.
So your pregnancy is always 2 weeks smaller than what is being calculated by the doctor.