It appears from your photos that your aprons are tapered in a straight line from the waist down to the hem.
Here is a picture of how apron tapering is usually done.
The difference in the width at the waist and at the hips is equal to the difference in your splits.
For example - If your Hip measurement is 35 and your waist 27 then your splits would be something like...
Width of apron at the Waist = 13"
Width of apron at the Hip = 17"
The taper begins up at the waist straight vertical or slightly tapered outward.
It is smallest at the level of the top buckle.
It then tapers out to the Hips.
The line of the taper then forms a slight "S" curve down to the Hem where it is almost vertical again.
This "S" curve does quite a few things that result in the final shape of the apron and the look of the kilt.
First the taper allows enough fabric in the aprons to prevent the aprons from being pulled tight and creating a pucker at the Hip line.
Second the taper allows the apron edges to wrap around the sidws of the legs and not flip outwards.
At the Hem the taper creates a small problem of the fabric just under the apron sticking down lower than the hem. We solve this by folding up a small fold and stitching it.
You can follow this link to an excellent article written by Barb T. about these 'apron tips'.
http://www.xmarksthescot.com/forum/s...ad.php?t=40778
The 'S' curve also allows the kilt to sit properly. A Traditional Style kilt is worn with the top strap cinched into the natural waist (just under the ribs). The flare above the top strap is called Rise and is larger than the waist measurement. This flare allows the kilt to accommodate the ribs and always stay at the correct location.
Here is a photo of my Tewksbury kilt showing the Rise and its flare.
Notice that the smallest part of the Kilt is at the level of the top straps. This is the part of the kilt that cinches into the waist.
To shape or mold the fabric of the deep and reverse pleats behind your aprons is really simple in concept but sometimes takes a little finesse.
The secret is LOTS of steam.
I find that the better the fabric and the heavier, the better it is at molding.
The real heavy fabrics like this will almost be able to be molding into a sphere.
Lay the apron face down on your ironing board or even on a table or the floor which has a bath towel laid on it to protect your table. Smooth the apron and get it to lay as flat as you can.
Then start smoothing the deep pleat on top of the apron just as you show in your photos.
Now lay down your pressing cloth and hit it with a spritz of water to make the steam when you apply your iron.
You do not "Iron" the deep pleat down. You use the iron only to create the heat to make the steam. Steam is always the same temperature so will never burn your fabric. If you iron wool it flattens the fibers and leaves a shiny spot.
Now patiently steam the fabric until it is hot and will soften. You can then gently begin molding the fabric into its new shape.
I heat the fabric with the iron and steam and then use my hands to mold the fabric. I often use an oven mitt to keep from burning my hands. I start at the apron edge and work my way in to the pleat crease.
When I get to the crease the deep pleat is flat and the fabric in its new shape. LET IT COOL! Don't move anything until the fabric is totally cool and it will now hold this new shape until it is heated back up again.
I hope this helps with your problem. I know it was a long winded explanation but with aprons there is a lot going on and you need to understand the concepts of why you are doing something to then be able to apply those concepts in your design and sewing.