The best way to find the perfect tree for your area is to contact a government program or check out the information provided by the Canadian Forest Service, Natural Resources of Canada, or the Canadian Wildlife Federation. There is also a free app called My Tree that's free and quite helpful. The University of Alberta Botanic Garden should be helpful as well.
A medium sized tree reaches from 30 - 40 feet tall (9 - 12 meters). When selecting a tree pay attention to your local conditions including sunlight, rainfall, soil, wind, etc. which may very over a small area.
Several trees might work for you including a Dropmore Linden which grows 40' tall (12 m); Brandon Elm (which at 15 meters may be a bit too tall for you), and a Laurel leaf willow which grows to 40 feet (12 meters). Of course, you should search out more trees as this is a short list.