Well I wouldn't say I'm high elo :P but I am a player who worked my way from B5 last season to S3 right now.
Looking at your match history I think one thing that will help you a lot is if you try to focus your efforts more one a smaller pool of champions. If you keep switching it may make things a bit more fun but try to find a champion whose kit you find cool to play with and focus on learning the power spikes/combos/positioning specific to that champion. You'll also start getting a feel for matchups and what you can/can't do. Don't worry too much about being right on the meta because in bronze 5 you can carry with any champ.
Learn about trading (The first part of this video goes over some of that https://www.youtube.com/watch?v=Q0TmT9HJ6U8). Don't trade in their minions, don't go in to fight unless you know you'll come out ahead, so watch for moments when their skills are on cd or if they're focused on something else (csing) for a second so you can get free damage off. If you're not really sure why you're fighting with them except, "I just felt like I should at some point" then this is something you need to start thinking about. When will you be able to fight them and deal more damage than you take, if you do one thing then how will they respond. This links back to getting comfortable on specific champs, you'll get a better grasp of this the more you try it.
Positioning is very very important, and it's something that is scarily lacking in Bronze 5. Think in advance, "where do I need to be in this teamfight". For example let's take Vi(my favorite jungler, even though I don't really jungle :P). So as vi you're generally building a mix of damage and tankiness, this puts you in the anti-carry (bruiser) role. Your job is generally to us your q/r in and lock up the enemy carries with cc and damage to allow your team to wreck. That's the simple, now let's say that you've been doing ok, but your adc jinx is 10/2 with tons of cs while their team has a xin-zhao and malphite, maybe you should instead hang back a bit and peel them off your poor immoble jinx and keep her alive. If she stays alive then your team has a much better chance of winning the fight. Or let's say that they have lots of peel (vayne-leona-ahri-ezreal for example), it's a much better idea to try and roll through their team from front to back so you're going to be more soaking up damage bursting down their frontline (probably saving your ult) until you can work your way back. So these are good things to consider when in champ select and the loading screen. Think about the specifics of the early game, what your teamfighting role is probably going to be, and then modify your build accordingly (if you're diving then damage will be more appropriate whereas peeling/tanking go for tank items as priority). https://www.youtube.com/watch?v=AHQ0mB57UX8
Upgrade your trinket and place the wards in places you intend to be in the future. Seriously people say this all the time and it seems overused, well they're not crazy. For example as a theory I looked through your past 10 ranked games and found that in 9 of them(the tenth was off by 1) the team that won placed more wards than the team that lost. If you don't know where the enemies are then how are you supposed to make good decisions as a team? With an upgraded trinket you can have three wards on the map at all times. Wards will help you make picks to get back in a game, they will decrease facechecks, allow you to see impending reinforcements and back off, contest objectives. The list goes on and on. You shouldn't have to worry about sweepers to much as in most games the amount of wards on the other team are small enough it will be practically useless. Buy a pink for dragon or baron from time to time if you want to have control over it. Also if you're running through their jungle remember to place one or two deep wards, if you're close and think it's safe make a quick run in to do that. Ward for your laners to keep them safe, ward dragon and baron so they don't get snuck on you. Thank Riot so much because you used to have to buy wards every time you backed and now they come for very very cheap.
leaguecraft101's videos are kind of long and a the examples look out of date at this point but he has a lot of very good insights on league of legends strategy and understanding why to do certain things. A lot of what I talked about is covered in more depth in his videos (I linked some earlier). Even though mechanically I've been a pretty poor player it was learning strategy through his videos and watching/analyzing LCS that allowed me to get the edge over my opponents and climb(improving mechanically along the way)
Add me in game and I'd be happy to watch one your games and give you some feedback(I couldn't do it real time because Riot staggers viewers by 1 minute to prevent cheating, but I could watch and mention a few things afterwards). Good luck at working to improve!
Edit: https://www.youtube.com/watch?v=5PwPWdd-3bo this video is cool too, just found it