So.. Ive ordered a small size (Im 34C during and post pregnancy but my size is fluctuating by now I guess) and it fit perfectly well. The sizing guide wasn't confusing after all. The material extends nicely, the fabric is soft. Everything is great. It even held my spectra flanges nicely as I pumped (twice) full sessions.  But why did I state it being uncomfortable you say? Well.. I personally can not handle any sort of physical contact near my armpit area. I HAAAAAAAAATE things crawling or sticking up near it even if its for mm short. I hate tight skin fabrics near that area & thats why, ladies, I gave it a 4 not a 5.
I couldn't wear it for half a day without feeling the need to skin myself alive. And no, its not the bra, its just how I am in general.