LP Gains/Losses

I currently have over a 60% winrate, and I'm Gold 2. I climbed from Silver 3 in about a week and a half. I am currently stuck in Gold 2, and my LP gains have dropped all the way down to 18-19 a win, and I'm losing 17-18 a loss. It's really tough now since I'm having a hard time carrying unlucky games and teams. Like I said, I have under 100 games and over a 60% win rate, which was 70% just a few days ago. Why/how did my gains drop so much? I understand that winning should help, but even when my win rate was at 70%, I was only getting 21 a game, sometimes 22.