That sounds like running out of water.
Losing prime would show up after long periods of not pumping. What you have is going to be sucking air I think.
You might consider seeing what it would cost to get a 4 or 5 inch well drilled. The drilling would be not deep. If a shallow suction well worked mostly, drilling 40 ft would give you a lot more water accessibility. Ask for a budgetary price locally. Still going to cost a bunch of money, but no running dry. You use a submersible pump which is silent. Never any priming.
You would have a pitless adapter put in to keep the water below the freeze depth.
You probably would have casing and screen all of the way.
There are people who drill their own wells, but I think that is only suitable for people with a lot of time and not enough money.