Some cucumbers finally started to form, but they are misshapen and stunted looking. What should I do?
If you see disfigured fruit beginning to form, remove it from the plant. This is a sign that incomplete pollination occurred because of some stressor: any extreme of weather, for example, and also low soil fertility can contribute. Feed the plants, and water well. I use an organic liquid feed of seaweed and fish emulsion.
Note: The above assumes the plant looks healthy. If the plant itself, not just the fruit, is also stunted or disfigured (blotches on the fruit, foliage yellowed in a mosaic pattern, for example) disfigured fruit could be a result of cucumber mosaic virus, which is often spread by aphids and affects many other crops beyond cucumbers. Again, this would be a distinctive-looking phenomenon, not just a stray misshapen young fruit on a healthy plant.