That's what you claim is Islam's criteria when is comes to having sexual relations with underage girls.
1) puberty
2) consent
3) no harm
So by your logic and Islam's logic it is permitted to have sexual relations with a girl of 8 to 13 years of age who has reached puberty and gives consent as long as no harm is inflicted.
That is one f**ked up philosophy.
You're stating it's appropriate for an adult male to have sexual relations with a child who reached puberty at the age 8 to 13, and gives consent which is absolutely despicable.
Puberty in girls can begin as early as ages 8 to 13, but biological development or a child’s verbal agreement never makes sexual activity with a minor acceptable. Any sexual involvement with a child is abusive and illegal, regardless of cultural or religious interpretations.