I'm trying to figure this one out, too. I added this photo to a different thread about a different bag, and so was happy to see it get posted here with its own subject.
I don't think that it's IF or Kooba... I just scoured everything I could find and there's nothing close. It's driving me nuts. It definitely looks similar to Shelly Litvak's other bags, except I can't find anything else from Shelly Litvak with a shape like this. They're mostly totes, from what I could find.
I really hope someone knows or figure it out!