What was stopping BF/pumping like?

My baby is 8 months and she seems to be showing less and less interest in nursing. We just recently introduced formula and mix it with my milk because my supply dips so low when I get my period.
I still haven’t decided when I want to officially stop. She’s been eating solids like a champ. She eats like a 1 year old, and has shown a lot less interest in milk. (I know it’s still the primary source of nutrients and we are still trying to enforce this).

I think in a few months I’m going to stop. But the thing is I don’t really know how? Do I just wake up one day and stop pumping? I imagine not….havign had mastitis before I definitely want to be cautious.
I want to nurse her for comfort but stop pumping and worrying about how much she’s getting. What was stopping like for you?