You may have enough room for a tabletop studio, but for a portrait studio that space is probably way too small. The absolute minimum space I would consider for a usable portrait studio is about 14 feet wide, 20 feet long, and a ten foot ceiling.
Depending on how you mount backgrounds, you may need a couple of feet between the background fabric and the end of the room. You may be able to buy/build something to mount the background fabric close to the wall, but conventional background stands need space.
You'll want at least six feet between the background and the subject. This allows for lighting of the background and the ability to keep the background somewhat out of focus. Lighting the background with a light placed between the subject(s) and background is often far superior to lighting the background from the side.
You'll want the camera to be at least eight to ten feet from the subject(s). Bear in mind that camera support such as a tripod as well as the photographer take additional space behind the camera. Let's figure three feet for the tripod and photographer behind the camera.
Add up the distances needed for the length of the space: 2 feet for background, 6 feet to the subject(s), 8 to 10 feet to the camera, 3 feet for working space around the camera. This totals 19 to 21 feet for the length of the room.
You need space on both sides of the room - typically beyond the limits of the background - for your lighting equipment. Assuming you'd be using a standard ten-foot-wide background, this means at least a 14-foot width for the room. Obviously, if you want to limit your background to six feet or so width for a single subject then you could get away with the ten foot room width. Even that would be quite crowded, though.
A nine-foot ceiling would work, but higher would be far superior for group portraits.
Mike, this was something I had stored away. Sorry the distances are not in meters, but one meter is slightly more than three feet.