Is what the questioner is doing — making up for missed fasting days and prayers after his repentance — correct, or should he do something else to absolve himself of the prayers and days he missed in several Ramadans due to masturbation and ritual impurity, especially since he does not know their exact number?

We hope that the amount of prayers and fasting you perform will be sufficient, as long as you intend to make up for them in an amount that you are certain will clear your conscience, with an increase. However, you should not limit yourself to making up only one day's prayers if you are able to make up more. It is sufficient to make up two days' prayers or more in a single day. Making up one day's prayer in one day is not sufficient, unless one fears for the welfare of his dependents.