Jennifer Staines, 23, used the name "Jason" on social media to contact three girls, two of whom were aged between 12 and 17.
After one victim's mother raised concerns, police found Staines had used a rubber penis and condoms during some assaults, the Bristol Post reported.
She admitted sexual assault charges at Bristol Crown Court.
In court, it was revealed that Staines, of Lostock Hall in Preston, had been on holiday with the family of one of the victims, and had to hide when she was using the toilet.
Another victim said that sex with Staines "didn't feel right" and happened in the dark.
Her deception was uncovered when the mother of one of the victims contacted police after suspecting a  social media profile was fake.
It was this profile that led her victims to contact her, meet up and begin relationships.
Avon and Somerset Police said Staines had engaged in an "appalling breach of trust" and had "manipulated her victims".
Det Con Nadine Partridge said: "Her actions were driven by her own selfish desires and although her victims 'consented' to sexual activity with her, they were deceived about the true nature of what they were engaging in.
"The manipulation was so extreme that one of her victims still struggles to believe she was actually in a relationship with a woman, not a man."
But police said it was possible there could be more victims and encouraged get in touch.
"I believe there may be more victims out there so I'd encourage anyone who feels they may have been contacted by Jennifer Staines, posing as Jason, to come forward and speak to us", Det Con Partridge said.
"We're here to listen, believe and support you."
A woman who posed as a man to trick her victims into having sex has been jailed for more than three years.