[quote=Skai]
The only thing(sic) I can add to this is that she is only 17. I doubt she needs to worry about having a baby at this moment in her life.
[/quote]

For a normal 17 year old I'd agree, but she's probably been told her whole life about how she's the last member of a noble line of purebloods, stretching back to, blah, blah, blah. That combined with the possibility that her parents told her what her mom had to go through to have her, and the fact that she isn't developing like a normal woman makes it perfectly understandable.

I also came up with a medical explanation for her condition. I'll add later that Mark's lined up a position as an apprentice healer already for when he graduates, but for now he'll just try and help other students
The condition I came up with is: Improper Fetal-uterine development stemming from overuse of fertility [s]drugs[/s] potions by her mother. It's essentially a birth defect which caused the uterus(which is normally mostly developed, including eggs being present, in girl babies) not fully growing. That would cause hormonal problems, which could cause the androgynous appearance (especially post puberty) and the lack of strong magical ability, as low hormone levels can cause loss of energy, motivation, etc. in muggles. I've even made up a study about a muggle doctor watching his witch wife's hormone levels and magical abilities during menopause.
Her normal doctors wouldn't have read the study because a muggle did it.