I wouldn't be too concerned about your vine not producing fall color yet. Because it is fairly new it may not have had a chance to produce the yellow (carotenoids, carotenes, and xanthophylls) and red and purple (anthocyanin and betacyanin) pigments.

The leaves of my Roger's Red turned yellow/tan/brown the first fall but now turns red/maroon/crimson. The colors are so vibrant it looks like part of the holiday decorations. I posted a photo to the gallery section last April. Take a look.

PS. I don't fertilize. It's planted along a chain link fence in the yard - no amendments, just native soil. This is a big vine extending at least 20 feet in each direction. It even climbed into the grapefruit tree. So give yours room.

Here is a link that might be useful: