TDEE calcs and activity level setting

I'm playing around with some TDEE calculators to determine my optimal maintenance calories. I am 165cm and 53.5kg. I work 3 days a week in a desk job (with a short walk to and fro. Public transport, out to get lunch). I am home with children the other 2 days and on these days my days vary between housework, constant cleaning up after kids and usually a small out and about walk with kids, eg to the park. I sit down a bit but am standing / moving for a fair amount of the day. Weekends are similar to my non work days

I exercise daily with a HRM and numbers vary each day depending on the activity and I would prefer to add exercise in on a daily basis rather than as an average for the week. (and will eat exercise cals in addition to the tdee calc I'm trying to determine).

What I am looking for is an average activity level to enter excluding my exercise. I had been using sedentary but wondering if it's too low.

Also, possibly a dumb question, but would wearing my HRM throughout the day give me an indication of my activity levels (again exc my exercise, eg taking the cals for the non exercise times)


Thanks in advance.