I think she is recieving too much love and care.
Bull Terriers are nasty little buggers. You should read up on what this breed was designed to do. Once you understand her thinking, you'll know how to handle her better.
Obedience, like what everyone else has already mentioned, is a major thing right now. I suggest you avoid training programs at petsmart and petco, they just arent equipped to deal with major behavior problems. You need a training class that is going to be a little strict.
I'm not saying to not show affection towards your dog, but there is a time and place for it. You need to put down the hammer, too. Being aggressive towards your pups (your kids), is unacceptable. You need to make her know that. I would almost go so far as to say that your kids and this dog need to be separated for a long time or until you have better control on her.
If you are scared of someone getting bit, buy a cage muzzle. They were designed to keep everyone safe while working through problems.
If you feel like this is too much work, I would advise you to find a BREED SPECIFIC RESCUE to rehome her. The reason I highlight breed specific rescue, is because you would be helping her find her "forever home".. shelters just move dogs and dont care where they go... if you even breath that she shows aggression towards dogs and kids, she is as good as dead... plus all this BSL crap ragging around.. bully breeds just dont make it well in a majority of shelters.
Contact a good trainer. Speak with your vet, look up trainers in your area through the AKC website. Speak with friends and family or neighbors.. There are a lot of training groups, you just need to start looking. And when you find a trainer.. tell them all of your problems and what your goals are. Your goals are either going to be reachable for that trainer... and hopefully they will be honest with you on what they can do for you.
I hope you can reach your little girl. I know how frustrating it can be to have problems with such a young dog.