Hello! Althea Is Taken For 21 Days Per Pack Right?

Hello! Althea is taken for 21 days per pack right? I've been taking it with metformin. Should I still take metformin even though I'm done taking althea or am I going to take it only when I take althea? Another question. Should I take my next pack of althea on my first day of period or should I take it 7 days after my first pack of althea? I have also been diagnosed of PCOS. Hoping for your answer. Thank you!