Possible pregnancy?

I'm two weeks past my period due  date and am on cycle day 45. I took two pregnant tests but they both came up negative? I also am diagnosed with PCOS and have irregular cycles but I've never had a late period for this long before. Is it possible that I could be pregnant and not know yet or did I ovulate late or not ovulate at all this month? Is dress a factor in my cycle being off? I'm worried.