Atlantia,
A friend who saw your statue commented that your statue is from the 1930 to 1950s and is a traditional Burmese Pwe dancer wearing the clothing of the Bagan style. "Pwe" Burmese word for a spectacular feast (theater, dance, music, marionette, etc.) He didn't think it was Sita, as she is the Indian Hindu deity, Rama's wife.
http://en.wikipedia.org/wiki/Sita
He also said there is also a similar lady statue in Burma known as the lady of Pagan/ Bagan...but he was unsure of the history behind this person.