Also note, that adding Prime just helps to neutralize the ammonia, not remove it. This is why test readings, as indicated on your note, will continue to show up.
As your pond is new, it has not fully cycled. Colder weather may slow the process. Ammonia levels can be more, or less, toxic, depending on the pH of your water as well. Continue to run your filter, and do not over-clean it. Added aeration may help if your fish are still continuing to gasp at the surface.
Not sure if you posted information elsewhere, but perhaps if you share the size of your pond and the number/size/type of fish that you have, it could also be helpful - on this thread.