Matchmaking and LP gain/loss

So I finished my preliminaries for mid lane after deciding to quit jungling. After my 8 games(6-2) I was placed in Gold 3, but have been teamed with and against silver players only even though I currently have 8 wins and 3 loss in mid lane I still only gain 17 LP and lose 18 LP, how so?

Edit: I win 15 LP now, after winning 17 LP my last game is the game even worth playing anymore? You can't climb unless you win two-three games per loss?