Italian master student looking for single room in Lisbon (IST, green metro line)

I am an Italian student of 23 years old, who is going to Lisbon to study Environmental Engineering at IST as part of the TIME agreement for two years.

People describe me as a polite and quiet person, and at the same time active and hard-worker. Thus, I would be looking for roommates who more or less could be described in the same way.
I am looking for a single room, with a monthly rent of maximum 350 euros, bills included. The apartment should be located within walking distance to the university or to one of the metro stations in the nearby (Arroios, Alameda, Roma, Areeiro, Saldanha, Praca de España, Campo Pequeno, Picoas, Entrecampos...). I would like to share the flat with maximum four other people, with at least a bathroom every three people. The bedroom must have a window to let natural light and air in. 

I have already lived abroad as an Erasmus student and so I am quite keen on flexbility and adaptabilty.

I am moving to Lisbon from the 12th September and I would be interested in an annual contract.

Please let me know :D