Music on iPhone 6 keeps disappearing! :(

Hi,

I've been plagued with a super -annoying problem ever since I got my new iPhone 6 a few days ago. I get all my music from iTunes and its subsequent Playlists to sync and transfer to my iPhone - then I can play everything no problem. BUT, when I sync my iPhone again, 98% of my thousands of sounds are deleted - the only remaining songs are those I bought from the iTunes store.

ARGGGGHHH!!!! I've done everything suggested in other threads about this - and chatted with Apple support but nothing works.

I've (not necessarily in this order):

A) Reset my Network Settings

B) Wiped all the music from my phone

C) Unchecked "Sync Music" from iTunes

D) Rechecked "Sync Music" from iTunes

E) Checked the option to "show only downloaded music" on my iphone

F) Wiped all music on my phone, backed it up then restored it (Apple suggested this.)

NOTHING WORKS!!!! I'm GOING INSANE!!!

So the key info here is that ONLY my songs purchased from the iTunes store remain. Everything else gets wiped everytime I sync it. So, in essence, I can only enjoy all my music for 1 synch. Then I have to repeat this wipe process and add all my music again, only to get wiped the next time I synch it.

HELP HELP HELP!!!!