21 year old girl looking for accommodation in Barcelona from August 2018

I'm looking for somewhere in or near the city centre. I just want it to be within the walking distance to everywhere really. Preferably with a double bed but will consider a single. Would like for the apartment to have a communal terrace if possible, but not neccessary. Preferbly 2 bathrooms if there is 3 or more bedrooms in the apartment. I want to be able to share it with a mixture of boys and girls who are also students and who are nice and fun!