I can probably give a better response later but this is just so I don't forget.

I assume this is your account: http://euw.op.gg/summoner/userName=bulwix

So I can see your duoing with other ADCs and whilst that's great I'd suggest you focus more on your own personal improvement. In saying that if you duo try to be on comms so that you can communicate more effectively to your team.

The champions you've played are Nami, Leona, Naut and Morg support. It's fine to play Nami if you can make picks on the enemy though I reckon most players don't actually play her well enough to make proper use of her. As such I'd say Nami is one of the harder champs to carry with unless you're quite a bit better than the average. I'd encourage you play more aggressive champs or at least play Nami more aggressively. Take Ignite and try to poke your enemies down you want to get your adc ahead don't just play passively and sleep on your lane.

I see you know how to play Blitz and Nautilus support from past seasons. I'd encourage you to return to those champions when you can because they have a higher carry potential as a support with easier ability to make picks and turn it into kills. Their lockdown is amazing in bot and can guarantee you kills eve if your ADC is slow. Your win rates are good on them and that was your highest ranked season. Take the preseason we are currently in to better learn your champs and learn the matchups in bot lane.

Botlane is harder because you need to try to communicate effectively with someone you don't know. Firstly treat your ADC like a bronze 5 player who is lagging in most cases. If you don't set expectations for them then you are playing to win the lane by yourself. If they happen to be decent then it's like a bonus for you. You gotta play for yourself. Hook and ignite to kill the enemy, if they can't get the kill early on then it's fine (its better to take the kill rather than let them escape on 1 HP).