Hi,
My bumbleebee has just perfectly shed today. A good 7 days after his mouth 'injury' from striking the enclosure top. Everything has healed now.
14 days would be a long time i think
I would suggest keeping the humidity up to 70+% all the time during shedding.
My enclosure is usually 60+% and i bumped it up by covering some of the open end of the enclosure top to get 74-76% during shed.
Btw, do u handle him frequently? try not to handle the snake when you see signs of shedding. this might introduce stress and interrupts the shedding process. I stopped handling my bumblebee as soon as i saw signs of shedding. only went in to replace the water but no handling at all until today.
aside from that, check if you have a reliable hygrometer and thermometer which is placed correctly (don't put it near or on top of the water bowl i think).
other than that you can try the pillow method or keeping him in a closed tub (with minimal air holes) with shallow tepid water for one hour supervised and then wiping him with a wet wash cloth.
i hope your snake will be alright!