Ranked LP gains/lose ratio

Sorry I dont know if this is really a bug, but I am posting it here cuz I think and feel it is. I have been playing ranked lately (all this week) I am Diamond V, was at 30 wins/27 loses at Diamond V (0 LP), I had a good win streak of 6 games on which everyone of it I won around +15 LP per game cuz at the end of those 6 win games I was sitting at 91 LP, then today I played again (according to op.gg) I was on an average MMR with my division (2175) , and had a win rate of 56%, then I proceed to play 4 games (lose 2 and won 2) first one I lose and got a -26LP and I was like hmmm what happen why -26LP, but was like ok... then play another one and won +19LP, the next one I won again and got +15LP (needed 19LP to reach series) so I kinda got trolled, but since it was not the first time on my life I was like ok.. ill win next one, then play and lost the game and got another -25LP and well this time I was like ok thats too much for having +9 more wins with a positive win ratio of 56-57% and an average MMR for my division, I think its too much to every game I win arond 15LP and lose around 25LP. How are we suppose to climb the ladder if u are winning 30LP on 2 games and losing 50LP if u lose 2 games, that leave you trying to win 3 to just recover what you have lost on 2 games. So I really think this is a bug or some kind of it, I even think I have read something on reddit about this happening.