If your mother became a citizen while you were under the age of 18 and you were living with her in the U.S. and had a green card - then you are already a citizen of the United States, and do not need Form I-130 or I-485. If you do not yet have a green card, it would make sense to have an immigration attorney review your case before you spend any more money on government fees.
Answered on Apr 20th, 2015 at 6:36 PM