A qualifying child is an individual who bears the requisite relationship to the taxpayer for the taxable year, who has the same principle place of abode as the taxpayer for more than one-half of such taxable year, who meets the age requirements, and who has not provided over one-half of such individual's own support for the calendar year in which the taxable year of the taxpayer begins.
The relationship test is satisfied if the individual is a child of the taxpayer or a descendant of the taxpayer's child, or a brother, sister, stepbrother, or stepsister of the taxpayer or a descendant of any such relative.
The age requirement is met if the individual in question has not attained age 19 (age 24 if the individual is a student) as of the close of the calendar year in which the taxable year of the taxpayer begins. An individual that is permanently or totally disabled as defined in IRC Sec. 22(e)(3) at any time during the calendar year is treated as meeting the age requirement.
In your case while you meet the age requirement test, the question is did you provide more then 50% of her support? If she returned home from college during breaks I think you will likely qualify to take her as a dependent since the value of the home, etc. likely pushes you will past the 50% mark. If not its more in the air since her income is similar to the amount you provided.
Because it is impossible for me to identify and consider ALL the relevant facts, this advice is not intended or written to be used for the purpose of avoiding penalties, and cannot be used for that purpose.