Sophia, while I think it's smart to take your time and not be rushed making big, life changing decisions, I would also caution about leaving the house unoccupied for too long.

JZ and her brothers took a long time to bring it to market and the place wound up catching fire and burning from an electrical short. Also thieves marked it as unoccupied and broke into it.

An unoccupied house is vulnerable in ways it's hard to anticipate.

Anyway, I think it's smart to get your BiL involved. He'll have a good sense of the house's value and you can weigh moving into it vs. selling it and perhaps getting something smaller and retiring early.