Looking for 1 room-flat around Düsternbrook, Brunswik or Altstadt

I will be a temporary female international (Portuguese) student at GEOMAR between October and December, I am a graduated marine biologist with a Master's in Marine Ecology. I am friendly, initially shy but social, respectful of others' privacy and living. I've lived in flatshare before and all I ask for is quiet at nights so I can rest the nights before school days, and no smoking inside the house. Ideally I'd like to find a place with WiFi, central heating, kitchen and the rent at 300€ maximum per month, just for 3 months. If you have any questions please don't hesitate to contact me. :) While I can't speak German, I can speak easily English, French, Spanish and Portuguese. Have a good day!