Should I take a full size bed, instead of a queen? My bf will visit me too ! I think I won't buy a couch, instead I was thinking of a futon. No way I have space for a couch ! haha
Have you considered a convertible sofa-bed? I lived in a tiny studio many years ago and loved the ability to have people over without the only thing in the room being a bed. Plus, it was way more comfortable than a futon...I've never found a futon that was comfortable to sit or sleep on but maybe I was just unlucky

You possibly should measure the boyfriend to see how small of a bed you can get away with 



One thing I do manage is not to have too much furniture. The previous owners of my house (which is relatively small--the original 1927 footprint of 1380 sq ft) crammed way more into it than I do. It's nice to see an expanse of hardwood floor ... and to have corners that can breathe rather than having furniture stuffed into every one.