How should one pray if she suffers from excessive gas and something similar to urinary incontinence due to repeated pressure on the vulva, and obsessive-compulsive disorder regarding purification? And can she pray Maghrib and Isha with a single ablution? What is the ruling on passing gas during ablution and prayer? Do the secretions that come down due to holding urine or contracting the vulva necessitate ghusl?

The cure for waswas (obsessive whispers/thoughts) is to ignore them and pay them no mind.

As for gases, if they are merely an illusion, then do not pay them any mind. However, if you are certain they have exited, then your ruling is that of one afflicted with incontinence. In this case, you should perform wudu for each prayer after its time has begun, or you may act upon the view of the Malikis, who hold that continuous hadath (ritual impurity) does not invalidate wudu, especially if this condition increases waswas.

As for the discharges you mentioned, they are not maniy (seminal fluid), and you are not required to perform ghusl (ritual bath) upon their exit. If you doubt whether what exited is maniy or something else, you are not obligated to perform ghusl, and you may choose concerning its ruling.

The exit of wind alone does not necessitate istinja' (cleansing after relieving oneself).