Do the contractions and discharges experienced by a girl while sleeping on her stomach constitute masturbation? And are the yellow, white, and transparent, viscous discharges, which cause no itching or odor, normal?

Sleeping on the stomach is prohibited. However, if there is no other way to expel semen except by sleeping on the stomach, this is not considered masturbation, because masturbation requires an action. Nevertheless, it is more scrupulous to avoid it and to distance oneself from anything that arouses desire. As for the discharge that came out, it could be manī (seminal fluid) or madhī (pre-seminal fluid), and one must review the difference between them and their rulings. Other discharges are vaginal moisture, which is pure but invalidates ablution.