Having Irregular Menses When Can I Expect My Next Menses?

Hi, I am on duphaston, 10 days a month..from 15th to 25th day of my cycle, since two months. My Husand and I are trying to get pregnant for the 2 months..I was put on duphaston and folic acid when an ultrasound revealed polycystic ovaries, however, PCOS wsa ruled out. My cyles are usually irregular. My last period started on 10th Feb. When can I expect my period based on this and if I dont get them when will be a good tym to do a home preg tst?