OTA channels in Ottawa

Hi,

yesterday I bought a really good indoor Antenna which is capable of receiving 4k transmission even at a distance of 70 miles away from transmitting tower. I attached it to the TV and could only get about 9 channels. I live in Barrhaven. I read else where that you can get up to 15 OTA channels in Ottawa. Is that true and if so, why couldn't I get all those channels? For example, I could get CTV two but not CTV's main channel. Should I change the antenna?