My granddaughter also can pee standing up like a boy does. When she sits she does tip her pelvis forward. I've always thought this is normal even tho it's different in my experience. We are all built differently. In a anatomically related experience, my daughter and I stained our panties in different parts of the panties. I think that is because our vaginas are located differently. She too would be mortified if she knew I wrote this. :):) My daughter has 2 children.
If I were you, to relieve any anxiety, I would ask the doctor about this at her next appointment. In the meantime, I really do think that the placement of one's "plumbing" can be different with each individual. I wouldn't be concerned.
Uterine placement also varies. Mine tipped backwards. My cousin's tipped forward. She had 4 children. I didn't get pregnant because of endometriosis which is completely unrelated to uterine placement and undetectible until way into adulthood.
I also think that the doctor could not determine uterine location based on where the vagina or ureter exits the body. This would require a vaginal exam and that is not recommended in a child this young. My daughter's pediatrician said that vaginal exams are generally not done until the child is an adult. And even if her uterus is placed differently that wouldn't mean she'd have difficulty having children. In fact I suspect that her uterus isn't in it's adult position yet.
My granddaughter, who is 7, is proud that she can stand at the toilet and pee like her 4 yo brother. Her brother usually sits so he can be like his sister. "Go figure."
There is an advantage to having the urethra outlet nearer to the front. She has "picnic equipment" as one of my male friends has said. When camping or away from toilets she can pee standing up which is much easier than squatting. My granddaughter has already done this when we've been traveling away from civilization.