When Hari assumed the form of a dwarf, she took birth as a lotus, and when He descended on earth as Parasurāma, she appeared as the Earth. At time of the incarnation of Rāma, she became Sitā, and when He was born as Krishna, she became Rukhmini. And thus in all the incarnations, she assisted Vishnu. When he had a celestial shape, she assumed the shape of a celestial, and when he assumed a human form, she took a human shape. She changed her body (human or celestial) according as Vishnu did.

In plain words: Sri always takes a form that matches Vishnu's. When he came as the dwarf Vamana, she came as a lotus. With Parasurama she was the Earth, with Rama she was Sita, and with Krishna she was Rukmini. If he is a god she is a goddess, and if he is human she is human.