I agree. I've had more female managers over the years than male managers, working in IT. But over the last decade or so, the numbers of female IT employees has dropped off sharply at the companies where I have worked.
In my first job, in the late 80s, I would guess 30% - 40% of the IT employees at the site where I worked were female and they made up over 50% of management grades at the time. At the last software house I worked at, the number of female managers was 1, from about 10 in total.
The last couple of places I was at, there were only a couple of IT staff, although at my previous employer, my replacement is female.