I am having a TERRIBLE time trying to get the side and zipper panels to fit the lining pieces of the backpack - I know I have to ease, etc. but there is SO much fabric and I just cannot make it fit. Freya (granddaughter) coming from California at the end of the week and I just CANNOT make it work!!! I have checked to see if pieces cut out properly and sewn together properly and all seems in order - HELP, please!