Have you checked around your area for frog activity? That would be the quickest way to know whether some might be on their way. Without seeing what the surrounding area is like, whether you're near natural wetland areas, whether there's barriers around, or at least another dozen other variables, it's too difficult for others to guess what the problem might be.

Not familiar with your area so had to look it up. From what you've said conditions should be okay for frogs in and around your pond. If they're not coming in it might mean that you're too isolated from their normal areas and they don't move across the gap. As you say, the small tree frogs probably have their water sources without needing your pond. I can't see there's really any way to make your pond more attractive to frogs in general to encourage them.

I never heard treefrogs in our neighborhood until we built ponds with no pumps and no fish back in 2004. Now we have hundreds of Pacific Chorus Frogs. You can transplant tadpoles if you are sure your pond has enough algae for them to eat. If it is too "clean" they'll starve....

Thanks for all of the comments! I don't even use chemicals! I'm about 1.5 miles from a wetland...so much is being built, it's sad to think the habitatss are getting lost. I sure do miss frog songs!

Well, if all fails you could buy one like I did ;))

I'm in central IL. For years frogs would just show up, then nothing. These last 4-5 yrs. still no frogs but come spring on a warm rainy week with a full moon Toads would show up sometimes a hundred or so. basically it was a toad mating part, anywhere from a pair to 3-4 in groups having sex. and the sound was always very loud day and night. then it will quiet down and maybe 1 would hang around. For about 2 weeks there would be strings of eggs. Right now I have hundreds to thousands little tadpoles about a 1/4" long swimming. In a couple weeks they will be all gone and tiny toads all over the yard. Give it time, they will find you..