Metformin for ttc

I have 2 children who were conceived naturally and very quickly. My youngest is 3.5 years and we have been ttc since March.. with the odd month off for one reason or another. Anyway I was diagnosed with PCOS when I was 16, in now 34. I’ve had metformin on and off for years to help relieve Pcos symptoms m. I’ve not taken it for about 5 years. So I’ve been to my Dr and asked to have it to help ttc. She said there is very little if any evidence that it helps women conceive but was happy to prescribe it to me as I have Pcos. So I’ve only been on it a week but I do feel really down about what the dr said. 
I have regular periods and I think I ovulate as I have a positive OPK every month between days 17 and 20 usually. 
Was just looking for some success stories or people who have used it and it’s not worked? 
We plan to try till the end of the year the. May give up. I’m thankful for the 3 healthy girls we have but feel like there is a baby number 3 out there somewhere waiting for us ❤️