This is because silver and bronze aren't that different.
You might belong in like silver 3 when you are bronze 3, but this difference isn't big enough for you to carry a complete team.
But if you actually do belong in silver 3 you indeed will get there. You might just have luck in silver, or bad luck in bronze either win in the end you should and will end up the same.
Always play to improve yourself, don't think you belong higher but think you'll have to practice to get higher.
What a lot of people tend to forget in this game is that you will most likely not be able to change your teammates, just change yourself!
I'm only giving my skype through PM. If you got added by someone claiming to be me verify it with a pm!