i dont see you missing any steps. Theres three bolts in the door hinges, at the door. It wont just fall off, you'll have to pull fairly hard to get it off. It common for the hinge bolts to do this in the A pilars. The nut is only spot welded on. Ussally you have to cut the bolt head off with a die grinder to get it apart. Fixing the trouble is a whole lot harder, as you have to weld a nut back on. If you have cowl panel damage to fix, thats the time to work on the hinge pockets. Alway tap out the holes (3/8 fine) before installing the door parts.

Jeff
1947 Chevy 6400 2-ton
In the Gallery
1953 3/4-ton
In the Gallery
It was fun while it lasted