Alright. So, as of right now, I'm a B3 ADC main, and I just can't seem to master it. Everytime I think I've got it down, I realize that I'm actually really bad at one thing, and once I think I've got that down, I look at another and realize that I'm still not good at it. Any tips? 
Main, BTW
what kind of tips are you looking for?
strategy? or mechanics? or item builds and their strengths and weaknesses?
ADC is one of the easiest roles to carry yourself out of with bronze, you just have to position yourself well in teamfights and do a lot of damage most of the time. Bronze players are bad at focusing ADCs. They either tunnel and waste a lot, which you can avoid by positiong well; or they ignore you and you do way too much damage and win the fight.
Also, I'd recommend against Caitlyn. She's appealing because she's safe, but her strength lies in turret sieging and fast pushing and she doesn't deal very much damage compared to most other ADCs. In Bronze you're unlikely to run into a team coordinated enough to siege turrets while protecting you, so it's better to pick ADCs that have high dueling and/or teamfight potential (graves and lucian are great).
All the champs you play are good in lane, try some that are more mid/late game focused
IMO it's extremely hard to carry games with lane bullys, unless you get like 4 kills in lane you're going to have a real hard time closing out the game. To get that fed in lane you're kind of relying on your opponents to make mistakes, which isn't the most reliable way to win games.
Whats are you concerns or area's where you feel you need to improve? I think we can better help you if you gave a little more detail. In addition I view ADC as chess, the entire role is situational. Maybe your making bad decision making at times or maybe your opponent is a bit more experienced as you an not making enough mistakes for you to capitalize on. So don't auto assume its you. If you need help with builds I can help you with those if that your issue in game. If its creep score related which is a big part of ADC then I recommend you practice in customs. So t really depends on what you think you need help with.
If you are having trouble with position etc. Try running some ARAMs with adc's. All the team fighting should help you learn to position yourself better. If not it's only an ARAM :).
Maybe try running a custom with your ADC of choice and see if you can beat the bots 1v5. If I have trouble with a champ I'll just do that to try out somethings. Sometimes it works for me.
