Getting less LP while winning :(

One of my alt accts running to gold again. Main is just gold so it's not like I'm full on hard stomping so LP/win matters to me! I started by totally bombing placements to maybe get bronze to play w noob RL friends but still got placed S3 then cruising up, but the more I win the less LP I seem to be getting :(

http://na.op.gg/summoner/userName=klrlus

26-19 W:L (lots of losses in placements) so I'm positive. Started by getting +28/win then lost a few, to +26 then +25 and now +23 a win while opponents are getting harder

Last few all running solo: Promo to S1 W-L-W then 1499 MMR: Us S1 S1 G5 Un G5 vs G5 G5 G4 S1 G4 (They favored) +25 1485 MMR: Us G5 S1 S1 G4 S1 vs G5 G5 G4 G4 G5 (They favored) +25 1509 MMR: Us S1 G5 Un G5 G4 vs S1 G5 G5 G3 G5 (They favored) +23

Why am I getting less and less :(