Female student seeking long-term single flat

I am a master's student in Berlin who also works part-time at Zalando. I am looking for a single flat at least 35 square meters starting January 2018 (flexible) for at least one year. I prefer the location to be 5km away from Alexanderplatz or less. My maximum rent is 600 euros warm (all inclusive). I will live alone. I do not smoke, do not have pets, and do not listen to loud music. I clean my home every week and make sure everything is good. I speak English fluently but can translate German if you do not speak English.