I had early interest. I'm male, and it began around age 10.
Interest beginning around age 11 for a girl does not sound all that unusual. Her level of intensity may be unusual, but that is just who she is, and it may be a component of her giftedness.
In my case, the objects of my interest were always considerably older than I was--as in, 5 years to a decade or two older. If your DD's interest remains limited to a boys only a few years older than she is, then that will be much easier to manage than my situation was.
All of this to say: Your DD seems just fine.
