Metformin making me NOT ovulate?!

So I’m officially dumbfounded. I was ovulating on my own prior to finding out I had PCOS last month. I have slightly elevated DHEA levels (no other pcos symptoms) so they put me on Metformin. Well a month later when I’m supposed to ovulate and I’m not getting a positive on my opks and no sign. I’m on cd17 and this is officially the latest it’s ever been. Why?! I thought Metformin was only supposed to help ovulating not the opposite? Super frustrating because I WAS ovulating on my own.. and now I don’t know if I even will on this. Ugh! Any insight?!