AF 2 days late but still bfn???

Hannah • Ttc Baby #1 :)
Hey just wondering for some advice. I am currently 2 days late for AF, but still testing negative. I have a 31 day cycle and this is the first time my period is late, I'm very regular. Has this happened to anyone? I haven't been stressed or anything, I'm on a relaxing holiday in Spain. 
I'm confused what's going on....