Janie Emery pleaded guilty to two charges of sexual activity with a child, involving intercourse, when she appeared in the dock at Mold Crown Court.
The court was told that the offences took place early last year.
During the hearing the 24-year-old, of Pentrefelin Terrace, Welshpool, was cleared of a third charge when the prosecution decided to offer no evidence against her. The court indicated that charge will be allowed to remain on the file.
Judge Niclas Parry rebailed Emery at the conclusion of the hearing, pending sentence in March.
The judge told Emery that she would receive credit for her guilty plea when the court hands down its sentence.
As part of the proceedings Emery was ordered to register with the police as a sex offender within three days of the hearing.
At a previous hearing last month she had denied all three charges and a trial date had been fixed to take place in May.
During the hearing on Monday the case was re-listed and Mr Andrew Green, for Emery, took the opportunity to ask for a sentencing indication from the judge.
He said that the defendant had her own vulnerabilities as shown in medical reports.
Judge Parry refused to provide a sentencing indication, which would be unusual in a sex case, he said.
But he told the court that he had noted that Emery had made full admissions to the police, and acknowledged that there were clear issues that needed to be addressed.
He told the defendant: "You know what you told the police."
The judge also warned that if the complainant had to give evidence during a trial then the sentencing goalposts would clearly move.
Judge Parry had initially rebailed Emery pending the start of a trial but later in the day the defendant's case was called back on when she changed her plea in respect of two of the charges against her.