Livebearer do tend not to drop all their fry at once, but in intervals, the intervals can be space between hours, days or sometimes a couple of weeks before they drop another load, which my swordtails always do to me, thats why i have given up with trying to put them in breeding traps...
Just keep an eye on her... because it hard to actually tell when swordtails are about to drop unless you know them in and out through their behaviour
Now since my swordtails drop 5 at each interval i let thm drop the fry in the tank and the net them out and put them in a brreding net until they are old enough to go into my breeding tank...
The most fry i have ever had is 23 at once, but i think it was three of my females that dropped at the same time (Yes, i have ONE randy male swordtail)