Is it permissible to adopt the ruling that does not necessitate making up missed prayers due to the turbidity (kudrah) that followed the menstrual period, and which was later determined not to be menstruation, in order to avoid hardship?

The view that the questioner is not obligated to make up the fasts is the view of Sheikh al-Islam Ibn Taymiyyah, and it is a strong view, and there is no harm in adopting it, especially if the questioner is afflicted with waswasah (obsessive whispering), so that it may help her to overcome it.