I'd like to offer a different perspective on that description:
As you mentioned yourself, she is caring and compassionate. The "uncaring" and "egoistic" label for ND is often applied unfairly. Many ND people do care and help others in need. But the difference is the control of the situation and the actual need.
Someone forgot their money and can't buy ice cream on the trip: person needs help, she feels sorry for them - she's able to help and does so.
Bringing sweets to the class: voluntarily and planned activity, also as others pointed out, class is a social situation you'll be in for the forseeable time; it helps to have your friends. On the other hand, NDers sometimes try to "compensate" for perceived "deficiencies" (feeling different / less), which is why they try to make up the difference with giving things.
Sharing items at home / with family: a different situation when home is the area where she can look after her own needs more.
In the case of the sweets situation, if her brother has equally many sweets as she has, there is objectively no need to share her own (even if her brother acts different). Each kid has the same amount of sweets. If her brother shares some, that's his decision. She does share in class, so why does she have to do it all the time?
About the toys: some people are very particular about things. They might also fear that items get broken when someone else uses them. Some people also have (irrational) fears about others using their stuff. Maybe they have bad experiences where someone else broke an item they were emotionally attached to. Maybe they like the way they arranged their possessions.
Why does it always have to be shoved down into people that they have to share everything / let everyone else use their stuff? As long as she can take turns on communal items like at a playground and is social and reasonable enough at school, I don't see why it would be so wrong to let her have some areas where she is in control and the things are only hers. As she proved with the help for the child who forgot the money, if a situation warrants it, she does share.
Her brother presumably has his own toys.