You must check with the local building authority; if you don't have signed off permits for the work, it won't be insurable.
Here in SoCA we cannot convert a garage unless we build another, or a carport. Offstreet parking is required. Now we have a garage but it is my shop and storeroom, so we could never get even one car inside. But it is still a garage and when we someday move out, it can be used as such.