Exchanging furnished 1 room apartment -> apartment with 30sq

I currently rent an apartment in Mainz Altstadt near Dom. The location is in quite center of the Mainz city, all super markets, many bus stops, many shopping malls are within 5min walking distance. This is fully furnished apartment. The additional cost of 150 euros includes the heating cost, internet, electricity. I need 1 zimmer apartment with minimum living space of 30 sq.mtr or 2 zimmer apartment withing the budget of 1000 euros as warm rent.