Nadya:
This time of the year is not an easy task. Sound like you are passing for the same experience that I pass 5 year ago when I first arrive to Ohio to find a job in Chemistry. There a lot of agency in US that like to get money from you without any garantee so do not apply to any agency that ask for money. A good agency is the one the get pay from the company that will hire you in the future.
Emmet is a good guy and Caspian Software is one of the best here in Columbus, Ohio. Hope hear from you soon.