Catalan PhD student looking for 3 months accommodation

I am Sara, a Catalan PhD student at the Polytechnic University of Catalonia in Barcelona. I am going to Berlin for three months to do a Secondment at a research institute and I am looking for accommodation to stay in the city from first week of September to first week of December. I am a sociable 27 years old girl, which already shares a flat in Barcelona. I am responsible, tidy and clean, and I like to cook and share good times with my flat mates if possible. I would like to find a comfortable place for my experience, so if you have a room and are interested in hosting a new roomie, don't hesitate to contact me. :)