Lack of potato production is due to too much nitrogen - either in the soil you have in the ground or are using in pots, or supplements you’re adding, or fertilizer you’re using. Compost (home made or purchased) is usually high in nitrogen, which you DON’T want a lot of for potato production.
Potatoes (all root crops; carrots, onions, leeks) require potash/potassium, so look for a fertilizer formula that is a 5-10-10. LOW in nitrogen (first number) and higher in phosphorus (middle number for blooming) and potassium (last number, for tuber growth/development.)
Thank you. Over-fertilizing may indeed have been my problem - such as using too much of my garden soil, which probably has too much of a compost component. I’ll have to give your suggestion a try this year.