Whilst I am not currently doing this, my experience from dressmaking & tailoring has shown that usually you are safer doing the clipping after the stitching. Also if you have a small seam allowance -1/8"- clipping is un-necessary. Also the angle of the clipping can make a real difference to the smoothness of the curve.
Normally we are shown to do our clipping as is drawn on the left-hand side of the above circle, this I find can give you lots of small points at the base of the clip when turned out..
If you clip as for the right hand side of the circle, I have found that these points tend to become eliminated - this I have mainly found on necklines, where for added smoothness I will clip each layer of fabric in the opposite direction and alternating to one another.
Even if this doen't answer your current problem, I hope it helps elsewhere.