If you can get you win loss rate fairly positive say 100 wins to 90 defeats then it it should start giving you better gains compared to losses.
That being said the 6 wins in a row were only enough to almost get you breaking even in in wins vs losses for ranked.
You are currently at 74 wins and 79 losses for ranked solo Que with 2 defeats after that 6 game win streak.
You are not doing super bad for your rank but you are not doing well enough to be moving up in rank and have an MMR above your rank. You need to be playing against players better then your rank to be getting better LP gains compaired to losses but you are likely against more bronze 4/5 players.
MMR is basically the skill level that you are playing at and not the rank/division that you are. In other words a gold 4 can have a plat 3 MMR and will be moving up in rank really fast for wins aka 30+ LP for a win and losing say 12 LP for a loss because they are facing people will above their displayed rank of gold 4. MMR is changed all the time and if you are consistently beating players at a MMR then your MMR will be moved up. Loss to it and you move down. In other words it will push you to be at a 50% win rate which is when your MMR is where your skill matches other players.
This i coming from someone who remembers being bronze in season 2. There is a way out but you have to accept yourself as the problem of being in the elo hell that you are in if you are to ever escape. And saying that you accept it is not enough, you have to actually work at it to get out andit starts with making better decisions.
In bronze you will have teams that make tons of stupid mistakes I know this is still true from games with bronze friends. That having been said if you can reduce the amount of stupid mistakes that you make, things should start improving for you.