Worried about daughter- sexual

13 year old daughter, year 8, worried she is too focused with Boys, possible she’s doing sexual things (kissing or more), headteacher called explained she’s concerned my daughter has formed a bond with a boy 2 years above her.

I am worried and really don’t know how to navigate this. I have had many in depth conversations with her but once she’s out that front door she’s a stranger, she’s very open with how her friends act and behave and the things I’ve heard are worrying, for example doing things with hands, with my daughters negative symptoms, like impulsive, eager to please, attention seeking, manipulative, want to fit in mentality etc I feel lost.

Help, advice, anyone else going through this?