Do you want a covered stoop or a porch large enough to sit on, say the length of the house?

Center your porch between the garage and the double windows.

With the cantilevered upstairs and full length upstairs window above the door, a forward facing gable isn't practical.

A flat roof would work -- as a porch large enough for you to actually use as a place to sit -- or just as a stoop/portico.

Alternately, you could create a nearly flat hip roof: from the center point above the door, you could create three roof sections with two ridges. Tried to get just the "hip" roof framing pic to come up but it wouldn't ... so ... it's on this page (you wouldn't need this much slope to your roof):

https://www.google.com/search?q=nearly+flat+front+porch+roof+with+three+section+and+two+ridges&source=lnms&tbm=isch&sa=X&ved=0ahUKEwijptLTnJjbAhUDpFkKHXHiCeYQ_AUICigB&biw=1366&bih=650#imgrc=z-3tvD8JrwOzWM:&spf=1526954467515

Found a better page for hip roof:

https://www.pinterest.com/pin/45599014950640861/?lp=true

Gosh - I think your house is adorable. Not sure what type of porch you are envisioning, but I would probably rework the landscaping and add a patio-type brick landing that highlights the entry and gives you room for a chair or two and some potted plants.