It's a little bit difficult to understand your text, but I will take that you currently live in a 1 room apartment and would like to move to a bigger flat in the near future (which you haven't found yet).
Zürich being Zürich, you might be able to find a flat in 3 months, or not. If you cancel your contract now, you have the risk of not having a roof over your head in 3 months.
Be aware that it's not just finding a new flat available to rent that suits you: you have to be accepted! You may read many stories in this forum of people who found their dream apartment, only to be refused by ridiculous reasons (among which the fact they are foreigners). Apartment hunting demands equal doses of skill, luck and
monies...
In my humble opinion, I wouldn't cancel the current apartment you have until you are sure you have a new one waiting for you. But I like to play on the very safe side when it comes to having a home in a foreign country...
In this kind of situation only you can safely balance the risks, Zurigo.