A bunch of people cover up most of the mesh top except just a bit for air flow, so it keeps humidity in better. The problem is your mesh top is letting the humidity out faster than you add it. I got some contact paper and covered pretty much all of the top except the corners I cut out for ventilation. I haven't had a problem with humidity since. Always at 55-60% without having to mist. Try that.

Good luck with the shed, too. My bp just got her blue eyes tonight, which I discovered when feeding her. I offered the mouse, and she struck and coiled. Then I was taking some pics since I got some film for my camera, and I was looking at her eyes and thought "hmmm her eyes look a bit different". I've been expecting her to shed for the last week now. Her belly has been pink and her eyes looked a bit silvery-black, so I knew it was coming. Didn't expect it tonight though. She took the mouse though. Hope there's no regurge.