Seven is an acceptable number. Probably the last she will lay. One good thing about laying that many eggs--it's a pretty good sign that she is healthy and on a decent diet. The low hatch and survival rate is a concern though. The ones last time--out of 6 eggs, how many were fertile? Only the ones that hatched, or were there some that died in the shell? How old were the babies that didn't survive? Newly hatched, or several days? Were they being fed?
Make sure she has a couple different calcium sources all the time. And several differnt food items. And when it's time for the babies to hatch, increase the soft food supply. If they feel there is not enough food, they will let the younger ones die. Also, be certain that she has clean water at least twice a day. It is probably the fastest way for the babies to get a bacterial infection, if the water is not clean.
Suggestion though--after these eggs hatch, remove the nest box or whatever she is nesting in. I do not allow my birds to go back to nest for at least 4-6 months after a clutch. No more than two clutches a year. Period.