In my experience, if a cat has a large fur ball in her stomach there won't be all that much room for food until she has brought up the fur ball, so a pot of grass, if she doesn't go out, is a good idea.
Some of my cats have been unable to eat one brand of dried food. They were immediately sick if they did so. I assumed it was either the colouring agents in the food or something else in it that they were allergic to. Changing the brand solved the problem.
Any cat that eats too fast, will be sick, so would we. So let her eat a little then take the bowl away for quarter of an hour, then let her have a little more. Repeat the process until she has had her normal amount of food.
I believe the current worming pills dissolve the worms entirely, so you won't see them in what she passes or brings up.