What should a woman do who does not know the boundary between the inner and outer parts of her vagina, nor how far a cloth should be inserted to check for purity from menstruation, for fear of affecting her virginity, and who does not know whether the wetness she feels has exited to the outer part of her vagina or not?

There is no need to exert oneself in searching for moisture, and ablution is not nullified except by the exit of moisture to the external part of the vagina. What is inside the vagina does not nullify ablution, and certainty is not removed by doubt regarding the exit of something. If a tissue enters and exits, ablution is nullified. It is not obligatory to wash as much as possible from the inside of a thoyyib's (non-virgin's) vagina; rather, she only washes what is apparent from it.