I am diagnosed with PCOS.
I didn't get periods until I was 16, and for the first few years I would be lucky to get one a year. In my early twenties they started to come a bit more frequent, but average 3-9 months. I have other symptoms of PCOS like fast growing hair, cysts on my ovaries etc and was constantly getting my blood tested for PCOS, but it always came back normal.
Last year, I had another blood test, and suddenly it confirmed I had PCOS. Another test a few months later showed the same thing. Yet now my tests are normal, but my OBGYN & FS say I still have PCOS, but my GP insists I don't and never did that it was just a fluke that 2 tests had the wrong results....so I really don't know how they decide these things. I've been dealing with it for 10 years now.
The one thing my OBGYN did was put me on prometrium (provera). I take it every 60 days and it forces me to have a period, because she said it's not good for the lining to build up that long. Also, it give me at least a chance of ovulating.
My FS also prescribed Metformin for the PCOS, and I conceived on the second cycle. I lost the baby at 10 weeks, but at least I know I ovulated and conceived. My FS said if the Metformin doesn't work on it's own, then I will take clomid as well, which she said should definitely make me ovulate. So...I think clomid should help, but there might be some additional things your doctor can do to help.
Good luck.