Does the skew lessen if you unbuckle that bottom strap? It looks like the skew is right at that level. If that helps, get rid of that strap altogether. The steeking is also right along that level, so if undoing the strap doesn't help then the steeking is at fault. As said earlier, redoing the steeking is not all that hard...you just have to get the lining out of the way. It is very easy to put the steeking in too tightly and get a bunched fell like you seem to have. Of course, this is a novice mistake and you should expect better from a professional kiltmaker.