Hey ladies. Hope you can help!

So I've been having A LOT of health issues but the main thing concerning me at the moment is my PCOS. I was diagnosed at 16 and have had in total 10-20 periods in the last 9 years. I have had only 1 the past 2 years. I was referred to a specialist who put me on metformin x 500mg twice a day. I've been on it for months now and my periods haven't come, no weight has shifted and it's making me feel like I'm broken. We're actively TTC so I've done regular pregnancy tests and monitored my ovulation. But I haven't ovulated at all :( how long does metformin usually take to kick in and regulate things? I have autoimmune disease and thyroid issues so my hormones are pretty much screwed anyway. What happens if the metformin doesn't work?:( any advice would be appreciated. :)