Hi Riptide94,
So there is an answer to your question. I am going to use your OP.GG page for reference here so you know in advance.
The first thing I want to say is that I see you play a lot of support, I myself am a Support Main also so welcome to the hell we live in. Though lets actually get an answer to your question for you.
So the game gives and takes LP when you win or loss (accordingly). What happens is that builds in your MMR. Your MMR is indicative of your rank in the ladder and says what your true skill is. If I remember properly, MMR takes into account various factors likes your Kills, Deaths, Assist - Gold Earned - Kill Participation and other things. Most heavily it factors if you win or lose the game. The reason why I state most heavily is that if you are playing very well consistently if you lose a game you will lose less LP then if you played poorly although you still lost, so you must lose some LP its just not as bad.
So why though do you only get +14 LP for a Win but -20LP for a loss you say? Well the reason is this. If you go to your OP.GG page (click on op.gg) you will see your page pulled up for you. This page will show your champions played, recent matches, and a lot of great stats to look over. At the top-ish of the page you will see Solo MMR. Now this isn't 100% accurate but this is somewhat worth looking at. When I ran your Solo MMR it showed me you rate as a Bronze 2 player despite being in Silver 5 currently. So when your MMR is goign down because you are losing a lot, the game takes more LP from you, that way you end up playing against people around your proper skill level. As you improve and win more games more often you will see that +14 grow. I currently receive about +22 LP for a win at Plat V and lose about -10 LP per loss currently. If I can keep my winning ways up I have seen it go as high as +25LP a game.
So does this mean you are a bad player? No, not at all. It means you are still learning the game, your role maybe, or how to carry a game. I do want to point out a support can very much so carry a game, so don't think that being a support player is the problem please. I have only ever been a support main for over 4 season now. If you would like some tips, advice and help figuring out what you can improve on to get that MMR up, please feel free to add me. My in game name is Xhibit. I am not amazing or anything but I am good enough to make it to plat and now working towards Diamond I hope.
TL;DR: If you are losing more games than winning, the game takes more LP then it gives. Which means you aren't playing as well as other people in your Division. Win more games more often and gain more LP per win. Same goes on the opposite end for losing. OP.GG is a great source of information for yourself and champions.
Best of Luck on the rift!