I do a ladder stitch ... and travel in the quilt as well as in the fold.
To be honest, I think it gives me a nicer finished edge than the way I used to do it.
Maybe trying other needles.
Perhaps thinner than you have been using? and sharper?
I know there are some needles I have that just do not "cooperate" when I am doing fine sewing.
After that, I think it is old stand-by answer ... practice!
If you somewhat "force" yourself to travel within the fold for a while,
I am sure that it will become more natural to you.