Autistic girls periods and puberty

hi my daughter is 9 and is going though puberty I have a feeling she may start her period soon. I’ve noticed quite a few changes obviously puberty and growth but behavioural changes as well the main one is she gets really emotional over nothing. I have sorted a bag aside with different sanitary products ready for when her periods start but as she is non verbal and has little understanding I can’t explain to her about puberty and changes all I can do is give lots off hugs when she gets emotional. Would any one like to share there experiences with me or offer any advice. Thankyou