Does Callie illustrate all the emotional problems that a person in real life would have in Middlesex?
The author did not interview or meet with any transexuals. He simply made Callie out of his imagination. What are 3 points on which I can focus to show Callie's experince with with gender dysphoria is accurate?
My first thought is that rather than trying to define her experience as "accurate," you should focus on whether it is "authentic." Keep in mind that no two individual's stories would be identical, and when it comes to portraying mood and emotion, there is no such thing as technically correct.
As far as the authenticity of Callie's experience goes, I would argue that yes, Eugenides does present an authentic characterization of his main character.
To look at the authenticity of Callie's experience in three overall points, I might encourage you to think chronologically. First, look at her childhood.
I was brought up as a girl and had no doubts about this. My mother bathed me and taught me how to clean myself...instructions in feminine hygiene were rudimentary at best...All was shrouded in a zone of privacy and fragility. (226)
As a child, with no visible differences between herself and other children, Callie accepts what she is because that is what she is taught. This is very normal behavior for any child.
But look at Callie as an adolescent and the feelings of fear and wonder she experiences when she doesn't hit puberty at the same time as her peers. Think too, how this confusion is heightened when she is not experiencing the normal effects of female puberty. Then, when she begins to have her first crush on someone, and it is a girl (the "Object of Desire"), she hides it. While engaged in her first sexual encounter with a boy she admits:
He was rubbing my overalls, but I was no longer in them exactly. My focus on the Object was too intense. (374)
She imagines herself inside the body of the boy who is with the Object of Desire, rather than inside her own body. This emotional detachment from herself is typical response of someone who is having a sexual encounter at a very young age, and is not ready to admit her true feelings to anyone, almost not even herself.
Finally, look at Cal as a grown man. His relationships with women are difficult. He admits to taking things very slowly. He admits to ending relationships just before things become sexual. He is still nervous and unsure of himself as a sexual being, and this naturally affects his relationships.
If you look at the entire book as a whole, understand that it is Cal's (Callie's) record of self discovery, which must go back to two generations before her. The simple fact that s/he feels it is necessary to even tell her story shows that her emotions and acceptance of such an unnatural and difficult life are authentic.