Padme is meant to be 14 in Phantom Menace. Even if she was Natalie Portman's age - 19 - she wouldn't be 17 years Anakin's senior.But then there's also the problem with the age between Anakin and Padme. In TPM Anakin is 8 years old and Padme is 17 years his senior.
Take from that what you will.
The issue with Anakin being so young in this movie boils down to Lucas saying that he wants the boy leaving his mother to be traumatic and acknowledging that this is more traumatic for an eight year old than a fifteen year old, requiring him to down-age the character. This does put a dent in the romance arc, but - in theory, anyway - I think it had the advantage of postponing the romance entirely to the next film and giving the arc the starting point that for Padme Anakin is still a little kid. Execution clearly left something to be desired, at that.