Is the lack of heart-felt reassurance after multiple Istikhara prayers and consulting with scholars who have issued a fatwa permitting work in an organization concerning which there is doubt, considered a waswas (whisper from Satan) or something else?

Taking precautions and avoiding doubtful matters is good, for the Prophet, peace and blessings be upon him, said: "Whoever guards himself against doubtful matters has indeed acquitted himself with regard to his religion and his honor," and "Leave what makes you doubt for what does not make you doubt." However, this applies when a matter is truly doubtful, such as when there is a disagreement among respected scholars, and not merely to illusions that lead to obsessive whispers (waswasa). Matters that are far-fetched and not considered doubtful are not among the doubtful matters that should be avoided; rather, this falls under waswasa. Scholars have mentioned examples of this, such as refraining from marrying women from a large country for fear of finding a prohibited relative, or avoiding the use of water in a desert for fear of impurity, or washing a garment for fear of an impurity that was not seen. It is not obligatory to follow every permissible opinion, because things are permissible until evidence for prohibition is established. Therefore, refraining from doubtful matters applies to those whose status is unclear, not to illusion and waswasa.