The stuck shed just sounds like low humidity, as already said possibly not your fault however, as you've had it a short time (and sounds like you are doing some very good things to keep the humidity up with the substrate and misting)!
As everyone has said, make sure to maintain the ambient air temp. at 80F you will notice the BP may be more active as well when this is changed.

Otherwise sounds great (apart from the breeder not responding to your messages...)

Best of luck with your new friend!