If you are using a fresh homemade pumpkin puree, make sure to strain out as much liquid as possible. You want the homemade puree to have a similar paste-like consistency that a canned puree would. You could be measuring your dry ingredients incorrectly. It is especially important in baking to measure flour by first fluffing the flour inside the container by gently scooping and releasing a few scoops. Then spoon the flour into your measuring cup without packing it, and level off at the top.