Sounds like you want to know more what a good clutch size is?
A good survival rate is +90%, a good clutch size is 20-30 depending on how large the mother is.
Sounds like you're doing just fine! Your fish will predate on some of your shrimplets, but I think with that thick HC mat, the shrimplets will have a good spot to hide and most should make it to adult hood. The main concern is once those fish figure out that those little red and white things crawling on the floor are very tasty, they will begin to harass the adults and you'll find missing eyeballs and missing limbs. Once that happens, you cannot untrain the fish, and your shrimp may hide a lot more.