[Ellie May]

I hope somebody has a suggestion for you.

Honestly, I don't think there is any food at any pet store that would meet your needs. Maybe Dr. Harvey's mix? (but not recommending that and it's probably online only).

All foods at pet stores are AAFCO approved (or should be) for healthy dogs. So they can't go below 18% protein. Even the 5.5% is much higher because it hasn't yet been converted to a dry matter basis.

I really think homecooking could work for you because you are already doing part of it. Preference may have vitamins and minerals, but they still don't seem to give any guarantee that after adding protein, it meets AAFCO (which may be fine if you are trying to manage a disease, but balancing is still pretty important).