Match making broken?

I don't know if this is the appropriate outlet, but I have to vent. I'm sorry in advance.

I've been playing this game for 3 years, and I've never felt angry. Like yeah, you lose some games and you win some games. Sometimes it's like a coin toss - when you flip a coin randomly, you'll get a lot of wins in a row and a lot of losses in a row sometimes.

But I feel like it's not the same this season - I'm irritated and venting, but I'd also like some feedback if somebody can give me a response.

I started this season placed in S3 for support - and I won 2 out of my 8 placements (in my first game I got an S, but had somebody on my team feeding so I lost).

Fast forward to post placements - I won 11 games in a row, and was receiving about 13 lp per win. Then I hit a terrible losing streak - game after game I was silver 2 and getting placed with people no higher than silver 4, and in many instances bronze 1. I didn't play a game with a single player of equivalent rank. After losing 9 games in a row (literally just finished the 9th loss), many in which I got an S and scored with KDAs of like, 5 in my favor, I'm down to like 40 lp Silver 4. (And to top it off - last game the other team had a Kat mid that was 21/7 with 197 cs, and our lux mid was 6/8 with 140 cs - our lux had a bounty and kat didn't).

I know this is an annoying rant and I'm sure people have them all the time, but if somebody could provide some insight or explanation or SOMETHING as to why this is going this way for me, I just don't understand the math and the mechanics of the match making.

Thanks for reading.