Experiences with metformin and cycle length

Hi, I was wondering if anyone started metformin then had extra long cycles? I've been taking metformin since July - had one period on it when expected in August, and haven't had another since. That one was 12 days long and when I mentioned it to my doctor she said that happens with PCOS and is probably just a coincidence. But I'm now on cd67, I've usually had 2 periods by now! It's by far my longest cycle in well over a year, has anyone had something similar?