How to post to instagram without quality going to crap

so i made a little insta edit, using my gopro 3+ black in 1440p. quality is good but its a tad shaky, but thats not the problem. so i use this app to make it so insta doesnt crop out the video so its the normal rectangular shape. so upon using the 'no crop' app and uploading to insta would work. its alright the quality is absolute poop. so then i tried just dealing with the square crop and uploading the orginal video to insta. the quality is still crap! is there any way to get around this or will i have to make my followers watch a bad quality video lol. in the instagram preview it looks really good but once i actually post it, it turns to crap. any help is appreciated and will get +k