Olly:
Is that a CMC or some other make?
If it's a CMC, then the hinges are attached with hex-head countersunk screws which can be loosened and the door moved all around to get it right. I've not used washers as spacers, but I have used small pieces of 1/8" aluminum as shims and they've worked OK.
The body side of the hinge is drilled/tapped into the frame upright and may not allow too much movement. The door side is attached with a small drilled and tapped steel plate behind the fiberglass and that end can be moved a lot by opening up the holes in the door glass (if necessary - usually there is enough slop in the holes to get the door right).
If you're just lifting the door straight up, then loosen those screws on the door side and try gently levering the whole door up, then tighten the screws just a little and get the door straight before the final tightening.
If it's not a CMC, then send a closeup of the hinges and maybe someone can help.
gn