Opinions/help please!

I have been dignosed with PCOS and have been prescribed metformin. I am 2 days late with my period and have no pre period symptoms (I usually have tender breasts and back and tummy ache). I have had a small amount of brown CM but that's it. I have done 2 pregnancy tests, both show negative but I don't feel like I'm going to come on. I'm sure you will all agree that you know your own bodies and can tell! We have been TTC for 2 years now. Am I just over thinking things and hoping too much? Should I face the fact that TWO tests are negative and put my late period down to the new drugs? I am usually fairly regular dispite the PCOS. Thoughts please! And please be honest! X