Request for a 2 Room flat for me and my family

I am a student at TU Dortmund in my 4th Semester. I have been living in Dortmund, Germany for 2 years. Now, my wife is coming to Dortmund so I need a bigger space for us. I am looking for a long term contract so that we can live peacefully. We both are of 29 years. We are quite and humble. We like to read books and travel. We don't smoke. We don't even have a pet and we don't even wish to have one. We both like to keep our house neat and clean on daily basis. We don't like loud parties. For us party means to have a good talk and dinner. I want a flat where there are atleast 2 rooms, bathroom, kitchen, balcony (optional) and the flat should be furnished with atleast basic needs. I am willing to pay 500 - 750 Euros (Warm Miete). I am hoping to hear soon some good offers. Thank you in advance