Did you put the mom in a breeding tank with a trap (or with java moss)? The mom would eat the fry.
For my guppies, one released 6 on the first batch, the other released 11. On the next batch, I usually got somewhere between 10-20.
No we don't use breeding traps. The first one was with her for a while and she didn't bother it...there are some plants to hide in too. then we moved it to a separate tank.
It has been 48 hrs since she had that one..I happened to be looking when it came out...and she is still really fat. I hope it isn't a retained pregnancy or whatever they call it. I'd hate to lose her--also the one baby seems a bit lonely in the growout tank we have set up (10 gal)