they should stay happy in the 10g. wait 2 more weeks and check out that gavid spot on the female(LARGE BLACK TRIANGLE ON HER BUTT). and pay attention to her during feeding. she may eat food and spit it out, stay near the botton, or even near the heater. these are sure signs shes soon ready to give birth. i recomend you buy a Lees's Bredder Box. I have the same set up as you and this has always worked great! good luck!
by the way yes, most of the time females are pregant when u buy them since many stores will not take the time to seperate the females and the males


