any advice on this please ?

Ok so I've had a hsg back in may 2015 came bk clear had a scan results were that I had some cist on my ovaries then was told there is nothing really to give me went to see my gynaecologist he said ok it looks like some times ur ovulateing some times not so...... put me of letrozole for 3 months still no luck partner when for first sperm test was 20% mobility with less than 2 million count we have been ttc for nearly 4 years now however I heard about something called metformin and woman have got pregnant straight away after taking it does annoy one gave any experience or information there could share xx