Perhaps your testosterone levels have dropped?
Libido seems to indicate that hormone in particular and young women have five times more testosterone than oestrogen, it's culturally known as being the male hormone, because they have more than we do, but it's still our most abundant hormone when young and declines with age more slowly than the other two because it's not as affected by the decline of the ovaries. I think it's made in the adrenal glands but I'm only a google reader, not a doctor!
Some GPs will prescribe it for women, others reserve it for men as it's off label for women currently.