Is it necessary to completely dry the vulva after istinja for someone who intermittently experiences air bubbles exiting from it, and can what exits from the vulva be considered air if one can control what exits from the anus?

This question arises from obsessive doubts (waswasa), and it is inconceivable for a person not to know if something has exited from their front or back passage, except due to extreme waswasa. It appears that nothing is actually exiting from you. Therefore, you must abandon these obsessive doubts and pay no attention to them. Do not rule that something has exited merely based on doubt. A person afflicted with waswasa may adopt the view of those who do not consider the emission of wind from the front passage to invalidate ablution, as a تسهيل (facilitation) for them. If you doubt the emission of wind from the back passage, the default assumption is that it has not been emitted. Do not rule that it has been emitted except with firm certainty, for the default is the validity of your ablution, and it is not nullified by doubt.