I've just had my bathroom ceiling skimmed and have painted with two coats of Dulux trade supermatt (thinned 3 parts paint to 1 part water). Once done there was a noticable bit in the middle that wasn't smooth (stripey bits), so I sanded back to the plaster, smoother it and repainted that part. Problem is I can now see the edge of the area where I've sanded although the paint used is the same and I did smooth it. I'm now not sure what course of action I should take. I had intended to put on two coats of a kitchen/bathroom paint once the undercoats were done, but I think I should sort out this issue now rather than hoping the top coats just cover it up. Any professional painters have any advice please?