Why am I getting less LP regardless of winrate?

When I decided to grind my way out of Bronze on my EUW account yesterday I got 26 LP on the very first victory. Then I proceeded to win 8/11 games, most of which in a row, but despite that I'm getting less and less LP with every game.

[sg-janna]

P.S.: You can check my account and stats via OP.GG or League of Graphs. Nickname is the exact same as this account's.