I have several suggestions about the plan you have so far.
Design aspects:
For doors and windows, you should try to maintain a minimum 3" of clearance on each side of the jamb of the rough opening. For example, a typical 2'-8" interior door has a rough opening of 34", that means you should try to maintain at least 40" between parallel walls that are perpendicular to the door. This will maintain enough room on each side so the door casing can be applied, otherwise you have a door with casing that has been butchered, and it looks like crap.
Try to place closets on interior walls or on walls that are not important for curb appeal. For example you have a closet on the front wall of the front bedroom, this will create an unappealing front facade. Any other wall would be better, then your windows can be placed on the front wall. The house will look much better this way.
When placing closet doors, particularly when the closets are very long, try to center the doors over the length of the closet, provided it works aesthetically. Not only will it look better, but the deeper portions of the closet will be accessible to the occupants. In instances where even a centered door provides poor access to areas of the closet, consider adding another door and/or consider splitting the closet into his/her spaces.
You don't currently have a designated dining area, this isn't a deal breaker as many homes of this size simply utilize a breakfast bar as the sole dining area, however, by creating a distinct dining space, you increase the functionality of the home. Of course in today's society, with the restaurant being the main dining experience, it may be desirable to not have one. This will be a judgement call, but if the space can do dual duty, it will fit both lifestyles.
The home is decidedly square. I don't know what the dimensions are, but you should consider whether the look of the home will fit into what you are expecting. While a square home isn't necessarily bad, it does give the impression of a box from the outside and it severely curtails the roof options, since a hipped roof design will look like a pyramid atop the walls, and unless that is your intent, I'm not sure that it works.
Laundry areas are a place where people seldom like to visit and as a result, it can be reduced in size, functional yet compact. In a home of 1200sf, there is no room for extravagance, and the space could be better utilized as pantry space or a second bathroom.
I'll leave it at that for the moment. In the meantime, I'll post a 1100sf plan that has 3 bedrooms, 2 bathrooms and a dining area, but it will take me some time to put it together.