It would help to see more of what you've done, but yours appear to be generously sized, which I would have suggested. A guy I rode with briefly found some very inexpensive grab bags that were quite a bit larger than the Mountain Feed Bag. I was envious...
A dedicated outer sleeve for bear spray, full-height outer mesh pockets, hydration hose keeper and one-handed storm-proof closure would be on my wish list.
Have fun widdit...