are my fish eating my shrimp

I doubt your fish would have taken them alive, but they may have cleaned up. Shrimp are more sensitive than fish generally are, so it could be something about your tank that wasn't survivable for them. Or they could be hiding. I have seen planted tanks that only looked like there were a few dozen in the tank until feeding time when hundreds of shrimp came out of hiding to feed.

What kind of shrimp did you have?

well crystals (they come in both red and black varieties) are the more delicate species of the two most common, caridinas and neocaridinias. (Crystals are caridinas, neos are like red cherry shrimp and their variants). You might want to read up on the specific water needs of the species and fine tune your tank to that. The fish will not mind or be harmed by the change and the shrimp will do much better. I am told pH is the most important number but of course you want all the other parameters in good control too.

I think you would have seen some debris, as in actual corpses not just shed shells, if they had been killed or died of poorly-tuned water. I have kept shrimp with a variety of fish and had no problems with attacks. If you had actual predators like sharks or something it would be a different matter but yours sound like peaceable vegetarians.

Therefore I go with the "they're hiding!" vote above. If, alas, these have or do come to an untimely end maybe try neos next time, they are a lot more resilient and not so fussy. But I love shrimp, have 2 tanks with pumpkin orange neos at present. Hope all goes well.

I agree them hiding is the most likely option
Water parameters/quality would be a more likely than predation if they didn't survive based on your stock list

From what I've learned over the years of keeping shrimp, TDS (total dissolved solids) and heavy metal levels are more important than pH. Generally, hard water with a higher TDS is more alkaline (higher pH value), but just adding peat or chemicals to lower pH doesnt effect the TDS rate and may not help you. Also, high copper levels will kill shrimp where fish wouldnt even notice. I'd buy test kits for heavy metals and TDS and check against your shrimp's species parameters before buying any more shrimp.