Hi bv, welcome to myBulova. I think these family treasures are priceless. I would be delighted to have a watch from any of my grandparents. I might go so far to suggest though that this was your grandfathers watch as it is a mans size for the period. It is possible though that grandma wore it or even owned it originally, either way you are most fortunate.
The case, I agree is Douglas and the movement is 21 jewel as a Douglas should be. As you know we do not have any ads showing this dial in a Douglas case. The clip below shows the Brunswick and the Douglas together. I'm stretching here but I see grandpa or grandma in a jewelry store with these two watches next to each other on the counter and someone saying, "I like this case and that dial...........", well it's possible I guess.
There is one other possibility, This is the 1946 Engineer. It's a bad clip at best.
It's also 21 jewel but in all the discussion we've had around this one the dial is said to have Roman numeral,
I'm up in the air on the ID, we have a tendency to label watches that don't match as Non-Conforming, it's possible that this beauty will end up there. At any rate, be proud of the fact that you have a wonderful heirloom.