Ride boots have a pretty decent reduced footprint. I wear Rides (size 12)and their footprint was the smallest of all boots I've tested. I only tried about 5-7 boots, and 2 of those were different Ride styles.
Your boot size is on the cusp of binding sizes. There is a different school of thought as to which is better, sizing up or down. Which school of thought do you want to belong to, and why? It boils down to your preference.
I can't really speak on the Flow bindings because I don't ride them, but I will anyways. I've heard that the 2014 flows have made improvements on the strap setup, but through design they can be a bit more difficult to step into due to a narrower entry in the rear. This is all what I've been told by a friend at a shop. This doesn't sound like your problem...or maybe it does.
Perhaps your boots are loosening up after the first run causing your problem to happen. Maybe try every possible entry method (foot angle in, toe height and heel height variations) at home until you can get a perfect fit on a consistent basis. If that doesn't work then head to a shop and start trying out new bindings and or boots. Or buy online and repeat all of these steps until it all works.
Thanks for that video, Neni. It will be shared, hahah.