Help !

La • I`m 23:) and we are ttc our first child
Ok so I have pcos, my doctor put me on provera to help me ovulate, she said to have sex the 7th - 10th day after your period, but I thought you ovulate before your period? I need help. I can't take opk because they'll show up positive even if I'm not ovulating, because of my pcos. Ladies  help me :(