PCOS TTC faint positive now getting negitive results! HELP!!

Hi all. I love this site!! I have been reading these threads for years i need some help and hopfully some of you have had similar experiences. Let me give you a brief history. I had my son in 2010 conceived fine. Pregnancy was text book. Fast forward 3 years we decide to try again for another baby. I did get pregnant but sadly had a miscarriage at 7 weeks. Since then we have had no luck so I Went to the doctors (as in that time I had put on alot of weight and have been having very irregular periods) I was diagnosed with PCOS  they recommended metformin which I have now been taking for 5 months. Periods regulated to 38 days on the dot untill this month. I am 7 days late but no period. It's odd considering my periods have regulated and have been on the dot. I took a clear blue test and it was negitive. I was emptying my bathroom  bin the next day and there was the faintest blue line! I thought it's properly a evap line however when looking into it there is alot of people saying that if there is colour then it's a faint postive. I went and got another test just a cheap one from Morrison and it is the strongest negitive. I am really confused!! I know I am prob clutching and straws and I want it to be the case. I have also read that woman with PCOS find it difficult to get positives results due to the hormone imbalance we have. I have have some symptoms such as sore boobs, waves of nausea and light headedness and peeing alot.has anyone else has something similar??