Carving heelside on a freeride board with softboots and low angles (relatively) is without a doubt, harder to do. Bending your knees deeply before you tilt the board up on edge is not going to help, contrary to what might seem intuitive, and to what some softboot instructors might say. You don't want your knees locked of course, but just bend them a little and lean the board over. Use your knees as shock absorbers, not just to "get low". Look where you want to go, and keep your trailing hand up where you can see it throughout the carve. Think about "feeding the dollar" - feed the board into the turn like feeding a dollar bill into a change machine. That is, start the carve on the front foot, and as the carve comes around, shift smoothly back and finish with about 2/3 of your weight on your back foot. All the while, remembering to not let that trailing hand get out of your sight. Board and body must rotate in space as one unit.
Good luck!