first time mom, first time breast feeding..

Zaira • God ☝🏼️ First ❤️ ✨Makeup Artist ✨ Married to an Awesome Man✨ 23 Years of Age✨ Expecting Our First Blessing✨👪
Hello ladies.. i need some help!
Yesterday my son started doing this thing where he latches sucks one time then unlatches and does that over and over again.. i know theres milk in there but i wonder why he is doing this?
It doesn't look like hes teething and no signs of pain either.. 
but he will sometimes get frustrated and wont eat at all🤔
Has any mom here been through this before?
Please any advise..
He is one year old.