I read in a book that my doctor gave me that your two weeks pregnant when you miss you first period.

It is only true until you have your first ultrasound. They go by the first day of your last period until then. If at the ultrasound the baby measures larger then your doctor may change your due date. It is possible that some women have a period like bleed when they are pregnant but it is not that common.

No, not excactly.

At the time of CONCEPTION, you are 2 weeks pregnant, according to the commonly used gestation calendar.

It comes from working from your last menstrual period (LMP) which, for most women is 28 days from your AF due date.

So, at conception, you're 2 weeks, at AF due date, you're about 4 weeks.