Is it obligatory for me to calculate the makeup days for Eid al-Fitr in Ramadan based on August 31st instead of September 3rd, due to the doubt resulting from Waswasah (obsessive whispering)?

What is advised is to cast aside obsessive whispers and strive against oneself to get rid of them, because succumbing to them brings evil and hardship. You are only required to make up the days that you are certain you broke your fast, and if you have already made up what you recorded on your phone, then do not make up anything else. Rather, cast away these obsessive whispers and pay no attention to them.