Rudy,
You're correct; the windshield is too small for the opening. The way i've fixed it on my builds was to add a 0.03" strip of styrene to the bottom edge, then sand it to fit. The BMF hides the color of the added strip.
On all of my builds of this kit, (4 or 5 in total), the rear window was always a bit large, but a little sanding around the edges was all that was needed to get it to fit OK.
I hope that this helps,