Hello, Welcome to HCM, I am Dr. Das
Firstly, When a woman is menstruating, then the endometrium of her
uterus is shedding out. That means all the layers are being excreted. After completion of
menstruation, the endometrium again starts to grow and during ovulation, it reaches to its maximum maturity after which it again gradually becomes ready for shedding.
From the above discussion, It is clear, that during menses, there is no proper endometrial environment which can enhance a
pregnancy. More over, ovulation, which produces ovum which is essential for pregnancy, occurs during 10 to 18 days of the menstrual cycle of a woman having otherwise normal cycle.
So, during menses, there is lowest chance of pregnancy. You need not to take any birth control pill.
More over, you have taken the drugs in a wrong way. It is not a schedule of taking this type of drug. It will make you cycle irregular and spotting may occur.
In fact, there is no chance of pregnancy at all.
Hope this information suffices.
Regards.