Maca Root and GNC Progesterone Cream

This month was my husband and I’s 3rd round of Letrozole 2.5mg. I’ve ovulated the last two months but this month I still haven’t got a positive opk and I’m on CD27. I went into GNC the other day after doing some research on supplements for women with PCOS that have helped them get regular and/or conceive. I bought the Maca Root Capsules 525mg and the Progesterone Cream. My question is, when should I start taking the Maca Root and the progesterone Cream since I’m on letrozole and still no positive opk? Also, how many capsules of the Maca should I take a day and is there a certain amount of days I should take it or do it through my whole cycle til I get a BFP? TIA! ❤️❤️