Only Getting ~80Hz Range on Pitch Antenna - Circuit Issue or Room Issue?

Hi everyone! I'm coming around to actually making a build I've been planning for a month or two. I can see the change in frequency from the pitch antenna, but my range is only about 80 Hertz from zero-beat to very very close. How can I fix this? Or do I just need to play in a very empty room?

Far:

Near:

For context, this is my setup for testing:

For context, my linearizing coil is 40mH, if that helps. I'm following this tutorial: http://www.thereminworld.com/Article/14695/a-diy-wine-box-theremin (with some alterations for the volume antenna, which I could not replicate). Any advice is appreciated!

I'm now thinking the issue may also be the breadboards. Even though I'm only using rows with at least one row between them, I figure it may be causing some stray capacitances. Just want some confirmation before I solder everything onto protoboards. Has this happened to anyone else?