About a month ago I planted some pothos leaves I had rooted in water, but I haven't seen any growth so far. Could I be doing something wrong or should I wait a bit longer?
The leaves look fine. Problem indications would be older leaves yellowing and dropping off. I suggest you move to higher light conditions and go easy on the water until it does start new leaves.
Epipremnum aureum grows outside in Mexico and most tropical countries so it can take high light inside a house.
An important detail here is to be aware of the potential buds in the axils of the leaves, where the leaf joins the main stem. The pieces will consist of a leaf joined to a section of stem plus the roots that were sprouted in the water. When we pot up the rooted cutting we are asking that potential bud in the leaf axil to sprout out and make a new stem. So the only clue that something is happening is to see movement by that bud changing into a weak stem and then producing leaves of its own. If the bud is buried too deep then you see no progress; either pull back the soil/compost or repot so that the bud is in light. Then as soon as it is ready to sprout the change will be readily visible.