Healthy, mature, non-melano females are always full of eggs. What you have to do is get the female to ripen those eggs and then release them, which starts with feeding her lots of high protein (mindset her into thinking it is a time of plenty and her babies will have lots to eat, along with getting her into top nutritional condition for making lots of healthy eggs). Seeing a healthy, active male betta helps get those hormones going. Many of the females we breed never get plump and fat-looking and yet they are able to produce fertile eggs, just takes them a few days of feeling that need to breed to get them to produce their eggs.