MMR broken

I did rank in season 6 where I was placed gold and then I took a break in season 7 to finally starting back yesterday in preseason. I did some good game and ended up winning 8 out of 9 but I'm placed in Iron and I get to be matched with around gold 4 players, I also have to climb with 32 lp per win, that's a lot of game just to be silver even tho it seems my MMR is with the mid-low gold players. Why. I don't remmember the rank system being this broken when I was playing a year ago.

Thanks for your time and sorry for the broken english I'm french canadian.