Tmi..? But please help ladies!

While looking to see if my boobs are bigger I noticed white flecks in/on my nipples.
It looks like dried/dead skin or something? Maybe the start of lactation...? IDK!!!
My period is due tomorrow.
Is that what it is? I've never been preggo before... 
I've had bfn up until yesterday AF due tomorrow I have decided to wait a few days after missing my period to test again.
Has anyone had this on their boobs?!?
Please help!!!