Completely understand your feeling

i am in the same shoe, and went through all your are experencing now. Mentally tired and i got a conclusion: no matter where it is, its always the same: company politics! Specially for people like us, as we are not native speaker and we have to learn the American Corporate culture... sometimes i just think better to be a invididual contributor than to be the management...

I learned an important lesson by being a manager in US Corporate enviroment - its not what you know, its who you know!