I have a question about lp as of recently

I have been on a massive winstreak winning maybe 17 of my last 20 games but one thing that is annoying me is that i am only getting 18 lp a win making me hit 94 lp every time but i also only lose 17 lp so i dont get wether my mmr is lower than my rank or if its a bug. But it should clearly state if my mmr is bad by making me lose more lp on losses or win more lp on wins. I dont understand why my win lp stays at 18 regardless of how many wins i get