HI, I'm Dr Steve.
Sometimes it is hard to know if a cat is done or not, but one good sign is that she is quiet and nursing. If she is not straining any more, that is another good sign. A slight discharge shortly after delivery is not unusual. Passing the placenta after each kitten is delivered is the normal process
I tell my clients that watching the mother for a few hours after delivering the last kitten is the best thing to do . This gives the mother time to gain some strength after delivery. It also gives time for discharges to stop and her to feel and act more normally. If during this period, you see her beginning to strain. that could be a sign of possibly another kitten and if she continues to strain and nothing is delivered within 1 hour, then she should be examined by a vet.
From your description, her delivery seems to be very normal and if she continues to be relaxed, doesn't strain and if the discharge becomes less, she should be fine. If she continues to strain or if the discharge gets worse or doesn't slow down in a few hours or if she isn't acting normally ( eating and drinking) within 8-10 hours after delivery, she should be see by a vet. Hopefully she is done and won't show any of these signs. I hope this has helped. If it has would you please click the ssubmit button so I may receive credit for my answer. I will check later to see if you have more questions. THanks for using just answer and good luck.