Hi dsideen,
If you go to www.tvfool.com and enter your address and height of your antenna it will give you the position of the towers you can then aim your antenna at those degrees.
Maybe your antenna just needs to be pointed differently to pickup those channels.

It will also give you the NM(dB) apparently by what I read anything -10 and lower will be tough to pick up.

I put a preamp on mine just inside at the tv to test and it did increase my signal strength will be putting it on the roof on the weekend.

Do you scan your tv every time you change your antenna position to see if you pickup more channels?

Hope you pickup more channels

Mary-Jane