well I have been with my db for about 2ys now and I naturally have cycles 3-4x's a yr due to my PCOS and I am now 10wks pregnant. I have no idea how it happened because we have never been pregnant before and we have never used any type of BC. It will happen just be patient and try not to stress. I know its terribly hard but when you least expect it, it will happen.
Seeing that you normally get your period every 2-3 months, you will most likely need (if you start clomid) Provera to help a period come on. I don't want to offend you when I ask this, but are you overweight, normal weight or thin? I only ask because if you are a little overweight, in some cases losing about 10% of your current weight will help with TTC. Also, I know how stessful it can be when you are TTC and thinking about having a baby, BUT sometimes when you ease your mind and relax...it helps big time! It sets a total different setting and sometimes when you least expect it, you get pregnant. It's good your on Metformin. Over time with being on Metformin it will help regulate your cycle, and also when you do get pregnant (because with those who have PCOS it increases the chances of miscarriages) you will take this up to your 20th week which helps reduce the risk to miscarry.