Do you think my dormers are big enough? This is what my house will look like. I would like them one foot bigger but the house planner says it can't be done because of the roofline,

They could be wider. One foot is only 6" per side.

They do need to be taller, or the windows should be shorter.

Do you have elevations? They would show if the dormers could be wider.

I'll also suggest removing the larger gable over the front door, and raising the porch floor.

Why the double gable over the front porch?

You are saying the larger gable is centered on the house, and the smaller is centered over the door?

I think a single gable centered over the door would look best.

The top of a typical window is 80" off the floor. Do you know this dimension for the dormer windows?

I assume there is living space on the 2nd floor and the dormers are contributing to this (floor area) and providing light and ventilation.

Added window at bottom of stair and widened porch.

Two small suggestions for the 2nd floor.

On left, move hall closet out, making bedroom closets larger.

On right, move bath door to the right, using space behind for a full height cabinet. You could also angle the door, from the edge of the tub so you would have a slightly straighter path into the bathroom.

And an observation. You are giving up much room for a large entry/stair hall, and upstairs in the open below space over it.

You might consider this too. Using a U shaped stair also puts the bottom of the stair in the center of the house, instead of out by the door.

I like simple designs and architecture that reflects the structure.

The stair would be about 80" wide, leaving a bit over 5' (64") for your entrance.

This is not a complete exterior, or interior suggestion, but just an idea how multiple gables might be used. It's also not accurate to size -- the entry area shown is much wider than 64".