Is it permissible to fast the first ten days of Dhu al-Hijjah and the ninth and tenth of Muharram with the intention of making up for missed Ramadan fasts due to menstruation, knowing that there are days missed from previous years that have not been made up?

The aforementioned days are valid for fasting with the intention of making up for missed fasts. It is permissible to combine the intention of making up for missed fasts with the intention of voluntary fasting in them to obtain both rewards, though it is preferable to intend the make-up fasts independently. As for delaying the make-up fasts for that period, nothing is required of you as long as you were unaware of the impermissibility of the delay.