So how it actually works lol:
You have a MMR for your games. It starts off at some value. You play against people of a similar MMR. If you lose your MMR goes down. If you win your MMR goes up.
When you play your Provo games you play with people around your MMR. If you win your games its a nice little +, if you lose well then you lose lol. It is very common for people who do their provo games to actually go DOWN in rank compared to last season. I am not surprised you got put into B1 again. Not because i think you are bad or anything like that, but because raising your MMR takes time. You are playing against and beat other people around ur MMR (regardless of rank). You'll need to constantly win to raise your MMR so that you can play against people of higher MMR and thus raise ur MMR more.
Hope that makes sense.
Sometimes its weird. Like, i haven't been ranked since season 3, but they still put me against people who are around the rank i had back then (low gold). Safe to say almost all the games are in my favor. So sometimes the system is weird, and getting from bronze 1 to silver V is harder than some other ones (so i've heard) but once you get into silver i think it'll be better.
TLDR: You played and beat bronze people so you got put in bronze. If you had a higher MMR and had played and beat silver/gold people you may of been put in gold. The people you play against is determined by MMR>