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.(If you have time...).
My guess is that you will see a big improvement.
I did give that a try last week end, and it did not really change anything on the digital Mount Mansfield channels. Still can't get WFFF-DT
WCFE-DT and american analog channels had clearly better reception though.
Climbing in the attic probably raised the antenna by about 8-10 feet. I only tried a single location, and roughly aimed the antenna. I did not take the time to venture in every spot and aim for the best reception in various locations.