We experienced a similar issues with our DD who is now 11 YO. Initially we discovered she had some mild hearing impairment, this was fixed with grommets. We found that asking the teacher to get DD to look and focus on the person talking would help, we called this "listening with your eyes". As well as helping deal with any issues of hearing through lip reading, it will create more focus For the child when they are given a command. We practiced in the home by giving small instructions, in a casual manner, starting with the "listen with your eyes as well, and look at my face..." then something simple like "go and get your shoes on".
Her behaviour, however, has always been challenging and we found that this was actually due to her being bored in lessons. She is now on the gifted and talented register and the school now recognises that she needed to be challenged more. Since they have been giving her harder work she has fitted in much better and is taking a much more active role in lessons.
The important thing is not to panic (I know, almost impossible, we did!). All children will learn at different rates, but if she sees you getting frustrated and anxious about it then she will and is will impact negatively on her progress.
I wholeheartedly empathise with you, I remember what I felt like and the worry we had. However, it does get better and you learn not to compare yours to others (the most demoralising mistake you can make!).
Work with the school, they will have seen this a hundred times before and probably with a couple of other children in your DD's year.