Unable to backup iphone ios 10.3.3 to both icloud or iTunes

Hi all apple fans out there. i recently bought a refurbished iphone SE(running ios12) and want to transfer my iphone 5 running ios 10.3.3 to my new phone.

backing up using iTunes(12.8.0.150 on OS X Yosemite 10.10.5 and 12.9.3.3 on Windows 10) came with a error " iTunes could not back up the iPhone because an error occurred while reading from or writing to the iPhone" . so i tried plan B using icloud(purposely bought extra storage just for this) and another error "the last backup could not be completed" both itunes and icloud error come out when backup left around 20%.

i checked my icloud and computer(tired with windows and mac) both of them have created the backup file already with around 14GB+(used storage on my iphone 5 suppose to be 25GB++). i tried everything google has to offer and non of them work. i do not want to buy third party apps(cost around 30-50USD) just to transfer my phone which is a waste.

is there any solution for this or this what have i have to stuck with ios 10.3.3 on iphone 5 and a fresh start on my iphone SE? appreciate all the help you guys can offer!