Right now, she is committing a misdemeanor (the less serious kind of crime) called "sexual misconduct" (see NY Penal Law Section 130.20). It is illegal for an adult to have sex with someone under the age of 17. So yes, she could get in legal trouble.Because you are at least 15, she may or may not be committing a more serious offense: it is a felony for a legal adult to have sex with someone your age unless the adult is less than 4 years old. Due to your birthdays, you may be technically not quite 4 yours apart, but generally, a 19-year-old is considered 4 years older than a 15 year old: if this matter were reported to the authorities, it may come down to prosecutorial or judicial discretion as to whether to treat her as less than 4 years older or as 4 years older.