Hmm. I could tell you live in a hilly environment by clicking on one of the stations in your report. Doing so pops open a depiction of the terrain profile used for the signal prediction. What a prediction can't account for are the houses and trees nearby.
Ken Nist's site has an excellent primer on siting antennas. Note that the scattering/blocking caused by trees and houses affects UHF more than VHF.
Siting your antenna to look through the roof is not doing you any favors. When the shingles get wet, they will retain moisture for a while and block/scatter more signal. If reception stays stable through/after some rain, then you will probably be just OK.
I would encourage you to review the site I pointed you to with your installer to see what alternate mounting location might work better. It could be just a matter of moving along the gutter a few feet in one direction or another or raising the antenna in small increments that gets you in a better spot. Good luck!