ABC in Dallas is on VHF channel 9. All your others are on UHF There's your problem. First off, Terk's usually overpriced for what you get, and amplification built-into a compact antenna usually kills VHF OTA signals.
If your situation doesn't improve by unplugging the amp and, if that doesn't work, raising the dipoles on your current antenna (raise the thicker areas first for a more stable signal), get a better, nonamplified, antenna. Try the Radio Shack 15-1868, for $25 at a RadioShack store, first. There's a knob on the antenna that can help you, plus the dipoles are better than most. Make sure that the antenna's closer to the window, if you can't get ABC in fine from where you want it.
If you can't get all the stations you want, report back here.