OH your not a horrible mother!!!
and BOO the child nurse thats her job!! cow!!

On the tin it also should say this is only a guide your child may need more or less then stated (along those lines)
she could actually need more to be more full..
you can over feed but thats where your feeding her just cause you want give it to her even if she isnt hungry but if she is searching for it she could actually be hungry
as for the day and night side it could be she isnt full enough to settle comfortably or try holding off her feeds in the day to stimulate her more and then feed her 20 minutes later and then also stimulate her while you are burping her by talking to her and etc..itms?
my dd sleeps through the night from 8-9 on wards and wakes at 7 for her milk and then back too sleep till what ever time she likes but as she is very tuny i offer her milk quiet alot.. and i stimulate her alot during the day i engage her and play with her do stretches etc.. but when it hits around 7 i start to do quiet time where i hold her and stroke her hair maybe ven a bath to relax her..