Good work and good Luck with the breastfeeding! There is nothing wrong with it. I am sure you have to have gotten this message from others so far.
Nursing before eating will help you with your supply for her - you can increase what she eats, and schedule more if she is very hungry, too. Your milk is giving her the FAT she needs to keep those neurons going gangbusters and making more to keep her smart.
There is nothing wrong with continuing to breastfeed - if she won't take a bottle, don't force it. It will only make her unhappy. She is happy with you, and that is fine.
My DS is going to get dinged for being underweight when he gets there, but he is healthy, happy, tooling around on his feet (which was why we didn't even raise an eyebrow when we went in for an early visit, and he had actually LOST a few ounces since his 9 month visit!) They are going to get used to using up calories when they are learning to walk!
DS's ped'n was all over us when he hadn't gained anything after leaving the hospital, then again after 6 month visit. No reaction once he started toddling/crawling/CLIMBING.
You have enough worries, breastfeeding your daughter is not one of them.
Please have patience with your Mom. She feels like my Mom: no control over the situation, and frustration because she can't fix it the way she did when HER pediatrician told her to when you were small.
Oh, I hope you find a measure of peace from all this, it is hard to pump and breastfeed and keep it going!
I wish you all the luck you need to keep this going as long as you both need it to.