Is it necessary to make up more days than expected, as a precaution, if the verification of purity during Ramadan was insufficient, and the questioner fasted days believing she had become pure?

When verifying a woman's purity from menstruation, it is sufficient to ascertain the cleanliness of the outer vulva. It is not necessary to insert a cloth into the inner part of the vulva. If you pass a cloth over the outer vulva and find no trace of menstruation, then you are pure, and you must perform ghusl (definition), pray, and fast. Your fast is valid, and you are not required to make up for the days you have fasted.