I'm in the same boat as you. Just focus on yourself though and do whatever it takes to win despite your team. Learn what items do what and how to use their active abilities. Learn your your own weaknesses too, it's really important because of two reasons; once you know them then you can fix them AND it's almost guaranteed that at least one person on the enemy team has the same weaknesses. Find that person and exploit them as much as you possibly can.
Find someone to main too, someone that you can enjoy spamming in every single game. It's best to main someone who can be played in multiple roles and who has a few different build options in my opinion. It's an added bonus if that champion either has a very high skill ceiling OR they have many exploitable weaknesses. For example, I main Teemo because he's regularly camped by the enemy jungler and he has no CC aside from his blind and his slow from his ultimate. He's also really squishy and needs to be self reliant. By maining him I am forced to not only learn where my weaknesses are, but I am also forced to correct them just to not feed my enemy laner; not even necessarily to win. Maining him forces me to improve as a player just to even survive and in just a few months it's done wonders. My map awareness has been improved because I'm constantly afraid of being ganked. My positioning has improved because I'm afraid of getting CC locked and bursted. My itemization has improved because I need to make sure I can survive or if I'm lucky come out on top of my lane match-up. I've gotten better at using item actives because I have to rely on them in order to run away or get kills. I have also improved at kiting for many of the same reasons previously stated. I'm still Bronze but I have been improving significantly. lol
Another word of advice is that we're in bronze; here you can't expect nothing from anyone. If you catch yourself thinking something like "we can totally win this 5v5 if Kayle ults me" or "we just need a good engage from our Amumu" or anything like that at all then avoid the play unless they specifically indicate that they are thinking the same thing. If you go ahead and just do it anyways though then you'll likely find tat they didn't do what you needed them to and then that's on you for the fight failing. Think of your team mates as nothing more than super minions who occasionally buy items and get kills unless they can PROVE to you that they are better than that. I'm not necessarily saying learn to 1v5 though either. Instead think of it like a game of chess. Your team mates are nothing more than dumb little pawns that are just doing their own thing. You're both the king and the queen and you need to focus on just two things...
"How can I avoid death at all costs?"
and
"How can I win, no matter the cost?"
Use your team mates to further your own agenda if needed, they might hate you for it but unless they prove that they are a better king and queen than you then you should consider them to be nothing more than bait to lure in kills for yourself with and ultimately obtain victory.
It's also important to realize that kills aren't everything. I mean sure, it does feel good to go 29/6/12 or some ridiculous score like that but it feels EVEN BETTER to gain that sweet succulent elo. Rather than think "how can I get this kill" you should instead think "what can this kill get me?" if you don't gain much of an advantage from going for a kill then it's not worth blowing your ultimate or your summoners over. Always be looking to take towers, inhibs, dragons, and baron's at any opportunity you get and always be looking like a hawk for those opportunities.
Anyways, sorry for the essay, I know the game better than I play it honestly but hopefully this helps you some! :D