Hello Sersi,
well I have lurked a while at this topic which even inspired me to start some slaanesh daemon army of my own (still WIP)

So a little suggestion here, get rid of the mechanical chair and the bondage things for the pregnant soul grinder. It looks too much over the top, too many legs and a multiarmed being on it, itīs just too much.

Use these legs instead for the spider like soul grinder you draw up/sculpted.
So instead of the spider legs I suggest you make some sort of disc/tableau for her to sit on which is carried by a horde of daemonettes or slaves.
You could fuse the hands or claws of the carriers to the disc or the flesh of the soulgrinder directly so that they have no chance to run away.
This way you combine this image of a "goddess of fertility" carried around/praied to with a horde of dedicated followers/cultists/daemons. I think that would be a very convincing and unique look.

You could also add some tentacles or loin clothes to the side of the disc so you donīt have to sculpt or use up too many mini for this

You could even have some cultists tramplet about and left behind on the soul grinders base.
Anyway keep going!
invivos