LP gains and loses

Why is that i lose 20-25 points durning every game i play, and when i win i only get 15-18,

And before you go off saying, my elo or wins and loses, are not at the right spots, i've already looked into that and my elo is right where it should be, and i have more wins then loses.

So can anyone else explain why i would be losing more points then i win.