Another thing to consider is that you might be doing it "backwards" from how your body wants to do it. When I first tried clipless, I put my left foot in first, and used the right foot to put down at a stopped position. I thought, well I am left handed, therefore I should be left-legged and since that is so obviously the case, I should use my left leg to push off then clip in the right once I get going.
NOPE.
After a couple of falls from trying to do this, I switched things around to see if that would work.
YEP.
Which leg you put down at a stopped position (if you aren't tricky with the trackstanding) does make a difference.