Searching for one room at Genf

I am a spanish girl, 19 years old student of laws, that is going for an internship to Geneva during the summer 2015.
The internship begins on thursday June 29th and lasts until wednesday July 29th, but I could adapt my schedule to other dates.
I am looking for a one room flat or a share one.
It would be preferable to be close to the Eaux-Vives area, but in the center of the city or around the hospital is also a good choice.
I will appreciate very much your answer with the availability.
Thank you very much.
Best regards.
Celia