Quick question.

When a girl begins Birth control (my girlfriend started yaz on the 6th of this month)

Is it normal for them to get there period a few days later?

She normally gets her period on the 28th and it is now the 31st.
Is it possible for them to completely miss their periods?

SHe is showing all her usual signs of her period, (and has been for 4 days). I know most people say but they are also signs of pregnancy, but she is showing the exact same signs she does every month.

Need someone who knows about it.

I wouldn't be so worried if it wasn't for her mom who is stressing her and i out about it.

She constantly shoves the calander in her face asking why her period hasn't come yet.

A little insight would be very very helpful