Patrice has the right idea, I think. A "messenger" style bag holds a surprising amount of gear. I have a bunch of actual "camera bags", but I also have a plain, nondescript, black sort of luggage bag, a cheap, cheap offshore-made one that I bought at either K-mart or Target, in the luggage department. It does NOT look like the messenger-style camera bags, because it is not. But it holds a LOT of gear, and yet, compresses very thin, because it is not padded.It is about 13 inches long, thee inches across the top, and 11 inched from top to bottom. It has a couple outside pockets, and inside has a mesh pouch on the lid, and it will "expand" when filled. The back side, outside, also has a mesh pouch.
Padding is overrated. If all you need is something to carry gear in, and you do not plan to slam it around, drop the bag, and throw it in ahead of you onto the car floor, then why the need for much padding? You can carry lenses in pouches or lens cases if they need protection. No need to baby your NIkon stuff. You ought to see the way newspaper guys treat their gear.