Looking at the general neighborhood from the ZIP code level, it looks like large trees are common. If you have large trees in the path, and based on how you describe the construction of your attic, I would suggest looking for a way to mount outside.
If WUVM on real channel 4 is not of interest to you, an RCA ANT-751 or even a Winegard FV-HD30 would perform well outside. If WUVM is a channel you want, consider a CM3016 or HD7015, both have low-VHF capability. I don't know if your existing antenna can be moved outside or if it is designed to cover both the UHF and VHF bands.
The ION affiliate, WPXA CH-51, is in the opposite direction from most of the other stations and may be challenging. Try one antenna to begin with. If that does not work well, a second antenna may be needed. I'm using SiliconDust HD HomeRun tuners and have a several fixed aim antennas.
http://forum.tvfool.com/showthread.php?t=820 If you do not get reliable coverage of WPXA with one antenna, the network attached tuner gives you a back up plan.