all of my audio purchases from itunes are stored on my iphone which is taking up all of my memory. can i back them up to icloud? i tried to sync with my itunes library, but the library on my computer doesn't contain all of my songs.

All of my purchases from iTunes are stored on my iPhone and taking up all of my memory. I want to store the music in iCloud if possible, but I can't get it to work. I tried to sync my phone to iTunes, but the library on my computer is all screwed up! I backed up my library to my harddrive, but now a lot of the songs aren't there and the ones that are there have multiple duplicates! If I try to sync my phone to my computer I'm afraid it will sync to the current library on my computer and I will lose all of the music on my phone! HELP this is driving me crazy!