Hello Nicolas,
I've had that same home built antenna. It can work well. Your problem with it is that ABC WVNY is a on real channel 13. That is in the high-VHF band. The antenna you are using current is tailored to channels 14 and up. That is the UHF band.
Additionally your issues with FOX WFFF is likely due to your home antenna not being a strong enough design. That is to say, a stronger antenna with better gain and capture ability of weak signals is likely more ideal.
Lastly, the US signals are best received with an outdoor antenna. Weak signals do not penetrate attics well. You are lucky you see some of them at all. Recommend outdoor installation for reliable reception of yellow shaded US signals.
If I were in your situation. I would have two separate antenna systems mounted on your roof. One pointed towards magnetic 115. An
Antennacraft HBU22 ought to handle your local Canadian signals nicely.
The second antenna I'd opt for an
Antennacraft HBU44, would be dedicated to the US signals. This antenna should be orientated to magnetic 170.
On the mast, mount the HBU44 at the top and 4' below mount the HBU22. Run two drops of coax into home. Terminate them in an A/B Switch. Example:
http://www.showmecables.com/product/...Fcg7MgodbA4AQg. Run single coax to TV. Are you wanting to serve more TVs?
This will in effect give you dedicated Canadian and US systems. My thinking is this: the US signals are weak and wll be most reliable by 1) mounting antenna outdoors and 2) Having an antenna being able to use all it's signal gathering ability focused on those weaker signals.
To switch between Canadian and US signals will just be a matter of selecting antennas.
Finally, I think wanting to scrimp on money may be detrimental. Buying the right antennas and equipment can be the difference between unreliable and reliable reception. As I've laid this system out to you, I am fairly confident you will reliably receive all green and yellow shaded Canadian and US signals with no drop outs.
Cheers.