Ok I will try to give you a relatively honest answer as best I can with my own limited knowlegde and experience.
Ranked is your best bet for a more consistently even field but you will have to play a lot to get placed properly.
As far as normals go I still say you are where you should be. For what ever reason things tend to go in streaks You'll lose for a while then win for a while and in the end you'll find you are right about 50%.
Just bc your teammates call you: noob and trash doesn't mean you are and it doesn't mean they know what they are talking about.
The reason you are doing best as sup is that being more patient is how you are actually supposed to play. If you watch the pro's they don't jump in lane run past the minions and stand still right clicking the opponent until some one dies, they farm, ward and wait for opportunities. I feel like you are actually playing better than your teammates, they are just blaming you when they screw up which is one of the hardest parts about playing sup.
I'm not very good myself but to pass on advice I have gotten from Better players you can try:
Play less champs, and try to focus on having not only a build but knowing what to build in different situations
Also (something I am super bad at myself still) Farming, if you can play safe and last hit more minions than your opponent while properly managing your mana you can win lane.
And don't worry so much about kills, farming, destroying turrets and killing dragons will give you higher levels, more Gold and buffs that make kills come a lot easier.
And if you want you can friend me and see first hand what bad at this game really looks like.
[galio-happy]
