Low LP gain

Ever since the end of the season I've been getting only 14 lp for each win and over 20 for every loss. I would understand if this happened if I lost a bunch of games when i reached gold 5 but that hasn't happened. I have a good win/loss and max losing streak is 2 in a row. I looked up my MMR and its normal for my league and most of the games, the other team has a higher MMR according to lolnexus. I just got to gold 5 like 2 weeks ago and have still been winning, it makes no sense to me. http://na.op.gg/summoner/userName=kageni