Bisexuality for teenage girls is usually not a sexual orientation, it's a manifestation of the same personality type where she would have joined the drama club or listened to emo music twenty years ago. Also, in the rare event she really does have sex with a girl, they're girls so it doesn't matter. (She's not going to get "in trouble".)

Ask your daughter to tell you when she wants a sleepover with someone she is interested in romantically and explain that you aren’t comfortable with that, not because she is lesbian, but because of the sex part with whoever. Otherwise allow sleepovers. Maybe she’ll be honest with you and maybe she won’t, but she will appreciate that you treated her like she was mature and capable of open communication with you about this.

Yes, no more sleepovers. Otherwise, I wouldn't change anything else.