Confused amount the amount of lp given out per win/loss.

Hi last season I was so bad at ranked, I had no clue what was going on. I didn't even use hotkeys like I just clicked everything. I got placed in bronze V after placements this season and I managed to get into silver V a couple of days ago. However I'm confused why I'm only gaining 15lp per win but I'm losing 20 or more per loss. I looked it up and apparently you should have a positive win/loss rate which I do I'm at a 63% win-rate right now (54/31). I dont understand why it's making it so difficult to climb for me when I've been doing well in the majority of my games. The only thing I can think of is can my performance last season come into play and be a factor on how much lp i'm losing?