Yes we do live in the city. Right at the edge as Steph said. I am three long blocks from city hall,my office. Tonight my office was my recliner. Needed to work but I do not like to work in the building all alone late at night and when I do have to I let the sheriff know. Living in the city still allows the critters. Our city is so tiny (about 165 people now) even the critters hardly notice it is here. LOL The dog that got the worst of it the first time is the one barking at them still. The other dog heads to the back bathroom to hide as fast as he can. We laughed at him so hard. I do not think he wanted to have to have another bath.

I have 3 kids (one going off to college tomorrow). They all have small rooms and taking another bedroom or putting stuff in the garage were not options and, though we have a family room, I prefer all their stuff in their rooms after they outgrew the preschool years. All of them only had twin sized beds but in each case we made the most of the under bed for either storage drawers or a trundle for sleepovers. Next I made the most of their closet space by installing a modular closet system so that I could store not only clothes, but storage bins for toys with smaller pieces or arts & crafts supplies. The combination of adjustable shelving paired with closet poles for clothes proved very versatle over the years because as they age, they always seem to need lots of storage, it's just the contents that differs. I also would include drawers as well and in two of the three rooms were able to eliminate the need for a dresser. All my kids have had desks in their rooms, the older two had a hutch top making use of the vertical space. I also tend to use wicker storage baskets in both of my DD's rooms which are attractive spaces to store extra stuff. I recently upgraded my DS to a double bed as I felt he could use the larger bed plus I could use it as a guest room when he is away at college. His room is about the size of your DD's room and it has really cut down on his floor space A LOT. I much prefer kid's rooms of this size to have twin beds. As they grown older, it becomes more important for them to have a space of their own to play and/or with friends. I do think there is some merit, though, to creating a separate homework/crafts area, if space allows, perhaps using the closet and a desk in the adjacent guest room. Here are my two DD's rooms which may give you some ideas. DD2 has a popup trundle below this bed which she uses for sleepovers. DD1's room is the tiniest at 9x9 so we made use of every inch. Bed is a captain's bed with storage drawers below. She is typical teenage girl now, lots of clothes, accessaries, sports paranephelia, and needs space for school stuff like books, supplies, laptop, etc. This is about as clean as it ever gets. The bones of her room, the furniture, was bought when she was around 10 and then we added the folding bookcase when she started high school. A few closet pics before we remodeled DD2's room:

I helped my best friend in a clean up and we managed to get rid of literally dozens of boxes of stuff! The first thing to do is take everything out and start with a blank space. Like you said, a cleaning day first. And I mean everything. Just leave the furniture where it's at. Even take the computers out-because then it gives you an idea of how to set up the office in a way that works better. Then get out some cleaning products and dust, vacuum and freshen up. Next up, get some empty boxes and plan to put stuff in them-garbage, recycling (if you have that), donate/give away, and keep. Then you take the stuff you took out and start sorting into those boxes. Once you finally get all the papers and assorted junk sorted, then you make sure to deal with those boxes right away-like take them out of the house and get them out! Then have her sit at her desk and think outside the box as to how to set up the computers. Just because the desk is aligned a certain way doesn't mean it has to stay that way. In my office at work I set up my space on how I like to work, not what everyone thinks should work. For example, It's said if you're right handed, put the work you're going to work on on your right. That doesn't work for me, so I keep my working on files on my left, and my out box on my right. So just get her to think of how things work best for her and set it up that way. Next up decide how she likes to work. I don't like drawers. I don't put things in drawers that I use frequently so I use them to store things I rarely use and keep those I use often within arms reach on shelves or on my desk. Again-thinking outside the box as to how I prefer things rather than how they 'should be'. This gives her a chance to feel more empowered about getting rid of things too. With my friend I had her go through all her paperwork and we sorted it into keep, archive, act on now and shred. She used to keep all her bills, even years after they were paid. We shredded tons of paper! Act on now went in a basket next to her computer. Archive, which was stuff to be filed was just thrown in to a box to be dealt with later. This was long term storage stuff-like her mothers estate paperwork or her divorce papers (she was divorced nearly 20 years ago!). She hasn't used this stuff in years, so it can just sit in a box until she's ready to go through it. Into another box we put pictures-knowing full well that she'd never go through that box but it was ok to keep it, but knowing that ONLY pictures were in that box, nothing else. So do something like that for your friend. She could probably use a task light-I see that lamp on top of the bookcase-it's obviously not used, so she can either get rid of it or actually put it on her desk to use. Those are places to start. It takes a lot of time and energy and I dont' recommend thinking you'll get it all done in a day. But like I always tell my friend-you eat an elephant one bite at a time. Good luck!

While I appreciate your desire to only add on in one direction, I would not want a public office space sandwiched between private living space and your master bedroom. I would add your new Master on to the bedroom side of the home, and the office beyond the laundry room. If you are living in the country, would it not be possible to create a separate structure for your new office? It might be connected by a breezeway to the original house, or even an enclosed corridor. I certainly would not want to have my Master right next to the new office.