cannot load windows via bootcamp assistant

Please someone help me before I go crazy

I have tried and tried to boot windows onto my MacBook Pro (13-inch, Mid 2012) running sierra.

I follow all the guides. open bca and have a 32gb usb stick. everytime it tells me there is not enough space on the disk!!!!!!!!

Ive tried to do it by partitioning the drive using bca swell but windows wouldn't load as it couldn't find files or something!

I have the 64bit iso file from the windows site.

why is this simple process so hard for me?

Also I've read that its easier on the new os so Ive tried to update but I can't see how to update my os. there is nothing listed on the app store as an update???

please advise!!

thank you