Let her be whatever she wants when she's a child, and if she decides she wants to be a boy when she grows up, accept your child, because when you have a kid you make a promise to love and support them no matter what
That is not entirely true. A parents job is to raise, protect, feed, cloth and provide shelter for children. While your doing those rules it is important to show love and support but also discipline and correct bad behavior. If your child ruins out into the road with cars driving you don't show love and support and let the cold do what they want. You get them as far away from the danger and instruct them why they shouldn't be playing in the street and then show love and support while teaching them correct behavior.
As a father of 5 children anyone under 10 shouldn't have to worry about sexuality or taught it besides that no one should ever touch their private spots. Protect and preserve your innocent children at all costs.
Teenagers need guidance, direction and supervision. Though I understand and accept that everyone has their own parenting methods, my opinion is unless your ready to be a parent you shouldn't be having sex. No need to rush into adulthood with all is consequences and responsibilities when you can wait another couple years and experience it for the next 90 years.
In terms of Transgender I won't share my full opinion, but I still think it is a massive decision. Larger then anything else an individual will ever make and if we don't trust individuals until they are 21 to handle making adult decisions then I don't think a teenager or even a younger child should be trusted or tasked with making a decision of this magnitude. If they have those tendencies let then experiment with it but encourage them with love and support to wait to make such a life altering decision when they are old enough to handle the consequences and results of such a decision. Their bodies are changing their emotions are out of control and once they are finally in control they can then decide I want to be something different. Encourage your daughters to be girls, encourage your sons to be boys and when they are adults and really can know the difference to make a real educated decision then show then love and support in those decisions.