Best food for sensitive stomach? Tried everything

My rescue has had stomach issues since I adopted her 6 months ago. We've tried:

- Blue Buffalo (diarrhea)
- Purina Pro Plan Sensitive (vomiting)
- Hills Science Diet (okay but lots of gas)
- Raw diet (way too expensive to maintain)

Vet says she's healthy, just has a sensitive stomach. She's a 4 year old lab mix, about 55 lbs.

What worked for your sensitive stomach pups? I feel like I've tried everything at this point. She deserves to feel good.