You have no more control over the emergence of these feelings than she does. Don't restrict your daughter's social activities, in the hope that this will negate her sexuality. Be aware that, legally, you will not be your child's guardian forever. This is true no matter the severity of the disability. Although state laws vary, in most states a parent's guardianship, or legal authority over their child, ends when the child is 18.
Sterilization is a difficult subject and a personal choice.
Laws vary from state to state, so be aware of them. Most states have followed a recent trend prohibiting involuntary sterilization of individuals, meaning that your daughter must consent to it. Information and openness regarding sexuality are important for healthy development. Talk about, teach about, and counsel on issues of sexuality and the responsibilities that accompany sexuality. Have open discussions about sexuality and disability with your daughter Acknowledge the social realities and the fears and uncertainties about their bodies and sexuality that many women with disabilities have.