Is your indoor antenna UHF/VHF? Would be fun to test your antenna in the Attic (Has high has you can) and compare with the result you had at the second floor.
My antenna is this one
It only has a simple dipole for VHF. In its current setup, I can barely see an image and sound on the analog channel 5, so I doubdt it'll be up to the task.
On the other hand, UHF reception is decent.
I'm planning on installing a better antenna permanently in the attic, but the idea of looking how much better the reception there for WFFF-DT is a good idea. If I ever do it, I'll let you know what my results are.