What should my secondary be

Alright I'm an older player been playing league for a long time, but I haven't played in about a whole year got real pissed uninstalled, but I'm ready to take another crack at it. I figure I've been going at this the wrong way......so I wanted some advice, I have my favorite champions but I think I like bot lane a lot but the issue I have is playing well with a support. If I have a good support or course I dominate and man do I dominate. But if I have shitty ass support at best I hold lane as long as I can and hope my support doesn't die too much. My question is simply I want to do bot I heard marksman are kind of in a bad place right now but still I like what I like. So here's my list of adcs I play as, Ashe, Miss Fortune, and Twitch, what should be my secondary role for me, I know them all but what would be good practice for when I can't get my main.

On a sidenote since these are my main adcs, any advice on champions that I should lean towards banning?

I'm leaning towards bot/sup but I don't want to be shoved in support role 80% of the time.

And is 3 adcs good or should I think about picking up maybe 1 or 2 more?