Q.pumpkins
Last year the pumpkin plant grew well, no signs of disease. I thought there would be many pumpkins but only one or two per plant.

It could be the variety your are growing, pollination and even environmental reasons for less fruit on the vine.
I too grow pumpkins each year and some years are good and some years are less!
These articles have more information.
https://www.gardeningknowhow.com/edible/vegetables/pumpkin/pumpkin-growing-tips-for-halloween-pumpkins.htm
https://www.gardeningknowhow.com/edible/vegetables/pumpkin/feeding-pumpkin-plants.htm
https://www.gardeningknowhow.com/edible/vegetables/pumpkin/pumpkin-flowers-but-no-fruit.htm
https://www.gardeningknowhow.com/edible/vegetables/pumpkin/common-pumpkin-varieties.htm