Is it permissible for me to repent from mistakes I made during fasting, such as swallowing excess water while rinsing my mouth, or stopping masturbation before ejaculation, knowing that I am very regretful and cannot make up for two consecutive months of fasting or pay expiation?

Expiation (kaffarah) is obligatory only for one who deliberately breaks their fast by engaging in sexual intercourse during the daytime in Ramadan. Swallowing mouthwash water unintentionally, and masturbating without ejaculation, are not considered things that break the fast. However, intentionally swallowing mouthwash water is considered a fast-breaker, but the fast is not invalidated by it if the doer was unaware that it breaks the fast.