Is this considered a whisper (waswasah) given the doubt regarding the intention of the oath, its type, and its timing?

A Muslim should not swear excessively, nor should they make an oath by Allah a barrier to acts of righteousness. Swearing by divorce is forbidden, and if a person swears by it and then breaks the oath, divorce occurs. It is not appropriate for you to swear an oath to avoid attending an Imani (faith-nourishing) gathering, which contains much good, for the Shari'ah encourages Imani gatherings due to their great virtue. If you doubt whether you swore by Allah or by divorce, then you must offer the expiation for an oath sworn by Allah, and commit to attending gatherings of knowledge, because attending them is better than forsaking them, as the Prophet, peace and blessings be upon him, said: "Whoever swears an oath and then sees something better than it, let him do that which is better and offer expiation for his oath." As for doubt concerning swearing by divorce, it does not effect a divorce.