One of the digitizers for designs like this said to use a thick loft poly batting. Some people had difficulty embroidering with it and used a lower loft. I just got my scuba fabric and am ready to try my first block.

I would try 2 layers of batting. Or if you have some Polar Fleece try as an experiment for thickness.
I have some thick poly stuff that my machine does not like.

Next time try wool batting over cotton bat.

Some use the Trapunto technique to get more thickness or depth in the design. You use two layers of batting (could be cotton/wool or cotton/polyester, or wool/polyester or others).

two layers, one wool and the other cotton or cotton blend.

This looks lovely as it is. One thing to remember is that the more quilting stitches you put in the flatter it will look For example, look at your outer flowers and they pop out nicely but where all the cross hatching is it looks flat. Personally I think the different dimensions add depth. Keep experimenting until you find the look you like.

I agree with the others I'd use s couple of pieces of batting preferably wool. ❤️ Chris

Saw something like this on another site. The digitizer used 4-way stretch material for the top to achieve a puffier look.

Fun design! Where is this design from? Interesting to learn about the different battings.

Hi-loft batting. It is polyester.

I agree with AnnaJar, the look will be more puffy with stretch material.

The more batting you use, the better the puffs will be. The fabric does not really matter that much. I have done many quilts blocks and used many different fabrics.

You really need to do some testing of different batting combinations to see if you get the look you want. As mentioned below, where the crosshatching is dense, the fabric is not going to puff up. Stretch in a fabric can go up and down, side to side, and diagonally. This can add puckers. However, I do know people ME on satin. You can post this on the Quilting Board and see what they advise. It's a very busy Board and they usually advise using two layers of batting.

https://www.quiltingboard.com/

Beautiful!!!!look at Stitch Delight designs..She explains our to do these blocks using stretch fabric

Zauberhaft!