22 yo girl looking for an accomodation in Madrid for six month

Hello!

I am Camille, a 22 yo French girl. I'm moving in Madrid to do a 6 months internship from January to mid-July. As my company is located on the Paseo de la Castellana, I'm looking for an accomodation not too far from this location (approximately 15 km). 

I am studying in a French business school (Kedge Bordeaux), but I just came back from a 1 year academic exchange in Sweden. There, I've lived in a dorm divided into three parts. I was sharing the kitchen, the laundry and the living room with 7-9 (depending on the semester) men and women. Before, I have lived for three years and a half alone in a studio, but now I just can't see myself living alone!

I'm looking for a flat-share with nice, fun and not too noisy people. I'm discrete and sociable, but I like to have some alone-time too. I would like to pay maximum 400€/month with every expenses included (water and electricity, and wifi would be perfect).

Thank you, and have a good day!