That's how I read it when I watched the film at the time of release but George seems to have had other ideas.
Here it states he intended her to be 11 (he slowly ramps it up to 15) when Indy had the affair with her (as if little Anakin and Teen Padme weren't odd enough) :
http://mysterymanonfilm.blogspot.co.uk/2009/03/raiders-story-conference.html