LP gains and losses are determined by where your MMR is in relation to your league rank.
MMR(match making rating) is, as the name implies, what is used to match you with other players. Each league rank(silver 5, gold 3, etc) have expected MMR ranges. If your MMR is higher than that range you will get more than more LP when you win and lose less when you lose. And vice versa if your MMR is lower than that expected range. This happens because your MMR moves faster than your league rank.
In your case I can see that you are silver 5 with 34 losses and 20 wins. It takes quite a bit of losing to actually be demoted. So your MMR is already likely in the bronze range, but your league rank just hasn't caught up to it yet(or down to it as the case may be).
If you want to improve your LP gains then you need to win a higher percentage of your game. Once you get to and maintain over a 50% win rate then you will start to gain more LP than you lose.