Re: Inverted or Concave Bob style
I have my hair cut similar to this! 
It is usually advised that people with round faces should steer away from bob cuts (or any really short hair cut), as it’ll only accentuate the roundness of your face. Although, if you got a bob with lots of layers and texture (one length would make your head look rounder) and maybe a cut without blunt ends (they make a round face look wider)… then maybe it could work… 
I would say that the best cut for round faces is some form of layers that frame the face and a choppy fringe (bangs) as they slim the face create the illusion of cheekbones. If you want the bob, try it with razored wispy ends which breaks up the roundness and adds angles where they don’t naturally exist. Oh, and get it cut a little longer than what you see in pictures..
Post a pic of the end product, whatever you choose to go with 