Only nursing in the AM?

Ca

I’ve been breastfeeding/pumping for my 9 month old since the beginning.

However, my supply has been dropping and I’m getting sick of hooking myself up to the pump 3 times a day when I’m working only to get like 2 oz per pumping.

I’ve been thinking about switching to our freezer stash and formula, but still nursing when we wake up for the day. Is that doable? Can you keep just your morning supply even if you lose your supply for the rest of the day? How long could I keep nursing just in the morning before I dried up?