15 dpo today cd 27 advice pls

Hello!

Glow says my usual cycles are 24 days on average (I honestly feel it's more like 26). Anyway here I am on cd 27 and AF not showed.. yet..I did a test yesterday at 1500 after holding for three hours and I had drank a lot of water - the test was still negative (Clear blue digital). Today I had slight nausea during a work out but I think that was cos o was hungry and had had a lot of liquid and bent forward. I'm thinking could the test have been false neg? do I wait til tomorrow morning and test again?

Thank you in advance - any thoughts on this welcome x