Re: lacking confidence
First of all, let me say that it sounds like you're doing a great job. So RELAX!! As they get older they get a lot better at emptying the breast more quickly and efficiently, so it's totally normal for their feeding time to get shorter. My daughter went from 20 minutes on each side to about 5 minutes on each side, seemingly overnight! It freaked me out at the time too, but it's normal, so don't worry. It's also normal for their weight gain to start to slow down as they get older, so don't be concerned about that either. It sounds like you have a nice healthy sized baby on your hands. It can be normal, too for them to drop a bit in percentile as they become mobile so if that happens in the next few months as baby starts crawling, etc, don't be too concerned about that either.
As for frequency of nursing, I wouldn't worry about overfeeding her. If she doesn't want it she will defintely let you know. If you offer and she takes it, then she probably wants it. If you think she didn't empty the breast at her last nursing I'd offer the same breast again. If it felt pretty soft and empty after she nursed, then offer the other breast. And don't worry too much about it because it really does even out in the end most of the time and unless you are noticing signs of foremilk-hindmilk imbalance or dropping supply then you are probably doing just fine.
It's hard not to worry at first when you aren't sure if you're doing things right. But it sounds like you are doing a great job! Keep up the good work!
“We are not put on earth for ourselves, but are placed here for each other. If you are there always for others, then in time of need, someone will be there for you.”