Confused? (Picture)

I'm sorry about the 'nudity', but in really confused about this line. 
It appeared about a week ago and has only got darker, and I've never had this before. 
Could it be due to hormones? My period is a few days late, so I'm thinking my body may be confusing itself and chucking out hormones. 
Is this normal? 
PS. I have posted about this before.