Someone had asked you how much sun your plant had because it looked a little light starved. I have to agree.
Your answer was: "They normally get a lot of sun here. Not too much though." Potatoes want full sun. If there is a "not too much though", then there could have been more? More sun would produce more potatoes, as long as the potato is still happy. If you water every day, as you say, it wouldn't have a chance to wilt for dehydration.
