Don't know about you, but my grandchildren tell me: "Grandma, your breath is "awful". In my case, the tumor was at the base of eso and top of stom so they had to take out the valve that keeps stomach contents in. I think that does affect my breath so I am using more mouthwash, mints, and try to stay upright a lot and keep acid reflux under control so the contents don't come up as bad. Your surgery wasn't that long ago, so maybe peristolasis (muscle action to keep contents in the stomach) is not up to speed yet.
Let us know what your surgeon says.