Replying to 3 trouble- specific

I looked at all the other threads and didnt seem to find anything that pertained exactly to this, if so feel free to delete. I am extremely comfortable spinning up to 630's off rails but I can even 3 a jump consistently. I am fine doing 180's over jumps of any size. When I do 1's I pop hard off my right foot and spin left. spin left. When I go to three I cannot figure out how to pop. I feel like I always start to rotate and catch edges as I take off, and if I do manage to whip it around (all penciled and stupid) I land laying on my tails and my shins are so murdered I'm in excruciating pain. What am I doing wrong? Thanks for any help