How many times must the Ramadan fast be made up for, with doubt concerning the number of times masturbation was practiced while fasting?

Do not pay attention to doubt as long as you have fasted, for the rule is that doubt has no effect after an act of worship. Focus on repenting from masturbation. We advise you to adhere to supplication and humble entreaty, distract yourself from the whispers that indicate you are afflicted with a type of them, and consult a trusted psychiatrist.