They are most likely breeding happily.
In fact, if you bought them as adults, many of the females were probably
already bred.
Gestation time is about 30 days or so, with live birth of anywhere from 20-40
nymphs, and then about a 10-15 day cooldown phase before breeding/gestation starts again. [which is why we just take a simple 20-25 babies a month average].
Adult females have a breeding lifespan of approximately 12-14 months, and newborn
nymphs take about 5-6 months to reach adulthood and start their own breeding.