I am not sure if I am the only one, but if I shove to tower while their ADC/Supp is in lane then back out for doubles, they usually shove to my tower and I lose more xp/money than I gain. Generally I do it on or after the cannon minion wave, but they will realize what I am doing and I will lose 2-3 cs to the tower and 1-2 from the actual shove(depending on my hp, boots, and if I am oom when I get to doubles). MF/Ez are 2 champs that I am very comfy on, but I do not like to play unless the comp is right. Everytime I MF/Varus I seem to get a dive heavy team against me with little to no protection.Some obvious shit - practice strong ADC's if they're not the ones you're used to (you mentioned Cait, she's great in pubs, so is Ezreal, MF, and even Varus if you're good at positioning). If you're blue side, farming those double golems whenever possible is also pretty big, push out the wave to their turret, go back to doubles, then return to lane as it resets. Solo queue ADC is hit or miss, sometimes their team comp can be dive heavy and if your team won't peel, you're pretty much fucked. Duo queue is definitely the way to go like someone else mentioned. I feel you on the MMR curve too, i've had to vs Plat 2-3's from Gold 4 and up.. and the skill increase is definitely noticeable. I've even had a few diamonds in my games, albeit I think that's moreso because they got diamond and then lost a shitton and are in platinum mmr now but whatever.
Perfect example of a slump game: 307 cs in a 30 minute game, 3 kills, 3 deaths, 8 assists. Nothing spectacular, but nothing feederish.