Thanks to your lovely recommendations, I have finally succeeded in enameling flattening discs. I use 19 gauge silver disc and one coat of counter enamel + 3 coats of enamel. The disc is not deforming (very slightly it does but thats ok). I am dry sifting my enamels.
The next challenge is a fully flat and smooth finish. I tried to place a laundry iron and press flat the enamel disc right after it came out of the kiln. This did not work and caused fishscale/deformation.
I have tried grinded flat and then reapply and refire but this also not feasible as it is a flat disc without edges and grinding/reapplying is also not yielding a flat surface.
I have searched for other solutions but have found little to no techniques to accomplish this.
Please let me know if you have any recommendations. I have attached an image of my progress!