I cringed the moment you said Teemo ADC.
I cringe anytime I see Teemo on my team in ranked period. It never works out. I don't like low ELO Teemo players in ranked. Every one that I have come across has picked Teemo against Pantheon or Irelia when our team could have really used a tank or a fighter. They don't pay attention to team composition, and they rarely influence the game as much as other top laners.
I'm a low ELO support main and I don't mind Vaynes for the most part. I never ever pick a passive support for Vayne though. The only babysitting support that works with Vayne is sometimes Braum. The defensive supports don't really give her anything because if a low ELO Vayne gets caught, she's done.
I know the majority of the laning phase is going to be me fighting off our opponents, so I typically pick a high AP poke support like Sona or a very aggressive tanky champion like Leona. Anything that gives her breathing room is gonna give your lane a better chance. As long as you make sure she knows that she's going to be AFK farming unless there's a gank, then you're going to have an okay time.
I feel like Vayne is one of those ADCs that has less room for error generally, and in low ELO that's hard when most ADCs don't even kite and only ward the bush next to them if Blitzcrank is on the other team, so I get the frustration. However Vayne's dueling capabilities late game are unrivaled, you really shouldn't underestimate her like you're doing.
If she's allowed to make it to late game smoothly, she'll delete everything very quickly.