[ADTech]

If you're back in "tight" to the back side of a sharply changing bit of terrain, the signal calculations become grossly overestimated, especially on UHF channels. If there are trees in the signal path, the problems gets even worse.

I put your location as a bit north and west of the intersection of Almaville and Spantown Roads, perhaps at or next to the Methodist church. You're right, quite a hill behind you in the direction of the main towers which are mostly located on top the hill on I-24 heading west. Two of the three stations you're receiving (WHTN & WJFB, virtual channels 39.x and 44.x (incorrectly identified as 66.x) transmit from Lebanon and are not terrain-blocked. WSMV transmits from a tower out on I-40 two miles west of the I-440 split and it's less blocked close-in by hills. That explain the three stations you're getting.

There is no direct correlation between actual signal power and the readings provided by most TV sets. Most internal meters display some product of the bit error rate and AGC applied to the tuner.

Simply getting the antenna out of the attic and up in the air would very likely improve your situation. Leaving any antenna in the attic will be a failure.