What is the sufficient manner for sniffing water into the nose, such that the water reaches the back of the nose, or is it enough for it to reach only the front of the nose?

In ablution (wudu') and ritual bathing (ghusl), sniffing water into the nose (istinshaq) is a Sunnah according to the Maliki and Shafi'i schools. It is obligatory according to the preferred view of the Hanbali school, and obligatory in ghusl but not in wudu' according to the Hanafi school. For istinshaq to be sufficient, it is enough for the water to reach any part of the nose, without needing to reach its very end or the throat. Exaggerating in istinshaq (al-mubalagha fi al-istinshaq) is recommended in wudu', which involves drawing water deep into the nose without it reaching the pharynx/cavity. We advise the questioner to be lenient with herself regarding istinshaq and to disregard any obsessive thoughts.