What is the ruling on one who has neglected to make up for the Ramadan fast for years, not knowing the ruling on making it up, and did not have enough time due to repeated pregnancies, and is she required to make it up even though she does not know the exact period she missed?

If you delayed making up the days you missed in Ramadan (definition) without a valid excuse (due to laziness) until another Ramadan or more passed, then you owe a fidyah (definition) (expiatory payment) for each day you delayed making up. However, if the delay was due to a continuous excuse (like pregnancy or breastfeeding) without interruption, then you do not owe aidyah, but you are still obligated to make up the days. If you forget the number of days, then fast until you are reasonably certain that you have fulfilled your obligation.