Don't feel so badly. I've been burning an F-B stove for years and you'd think by now I would have it all figured out; not so.
Getting ready for this heating season, I got the firebasket in, then the rear hopper plate, then the lower hopper, and then the upper hopper. All of the heaviest components were in. Then I picked up the grates; the items that should have gone in FIRST!
No harm done, only my ego was bruised.