@TS how you measure oil level? Engine cold, and parked on flat surface?
Do you change oil brands regularly?

To verify if engine is consuming oil (and not leaking away), check the spark plug, and see if any of it has signs of black soot around the tip. Change to other brands of oil, or those that you have used before.

Few possibilities with oil consumption, valve seal leak or worn piston rings.
Oil leak is another issue but mostly can determine from external inspection, or look at radiator coolant.

Some foreman will do what they can to save your money, meaning top overhaul with necessary works only - repolish block and new piston rings. Ask around.