I have always called myself an Interior Designer, although my degree I studied was Interior Architecture and Design. Back then (1993) there was a bit of a debate about the term, as architects wanted to protect their word but interior designers (the ones that look at how the insides of buildings could be better rather than the inside of rooms) want to distance themselves from the interior decorators.
Recently I have herd the phrase interior architecture used a lot more frequently as more interior architects are wearing there badge with pride. For me the most important thing is that Clients understand what you do and as the term ‘interior architecture’ becomes more well known I am sure the amount of people offering the service will expand. In the meantime I am glad to be called an interior architect or interior designer.