Do you have things poking out inside your kettle? Anything like a dip tube, thermowell, ect will affect the whirlpool.
Also, simple thing, are you going clockwise or anti-clockwise? If you're in the northern hemisphere, you want to go clockwise.
I notice on my big pot (15g) the whirlpool won't get the whole way coned up in the center. But it will get most of the trub away from the outer edge of the pot. I hold the autosyphon straight down against the pot. Once I start the siphon, I can see the trub going into the fermentor in the first few seconds, then clean wort. Once the level gets low enough in the pot, the cone of trub starts to flatten out. I pickup more trub in the siphon, but not as much as I would if I didn't whirlpool.
B