So glad to hear your progress!!!!!
It's typical of all dogs to only listen without distractions--it takes a lot of time and training to get them to listen everywhere. I've only worked with one dog EVER that actually was flawless everywhere without any extensive training. So here's what you do:
Start moving out of the house. Do some training in the back/front yard. If she's not listening to something, pretend she doesn't know it--for example, if you taught her to sit by raising a treat over her nose and back, and you're telling her to sit and she won't, don't say it a million times and get frustrated. Just pretend you have to "reteach" it, and do the same thing you did to teach it. In new environments you kind of have to think that your dog has temporarily gone completely untrained. You have to give them a reminder so they remember, "Oh hey, she's telling me to do something...that's right, that's what I'm supposed to do."
Right now she's a loooooong way away from being perfect at Petsmart, but a great place to start is a not very busy park. You might try a dog-friendly people park before tackling a busy dog park. Get a good distance away from the other park visitors--this may be 10 ft or a 100 ft. The further away you are the easier it is for her to not get distracted. Start here and do the same thing I described above. Once she has this down PERFECT, start moving a little closer to the main flow of foot traffic(but not right next to them yet). Move in tiny increments, and only move closer when she's listening perfectly at prior distance.
Keep in mind that you need to make yourself REALLY interesting--this typically requires looking like an idiot.
Squeakers, high-pitched voices, running away, anything to become more interesting than the distractions. One thing I've always done is run away without warning if the dog is completely unfocused. (Just be sure to have a long lead on them so you don't abandon them unleashed.) When they run after you, turn to face them and praise enthusiastically, and reward. Now try giving your commands again. If she's just REALLY not catching on at a certain distance, then she's just not ready--move further away from the distractions.
Only when she's perfect at a people park(much fewer dogs than dog park) should you try the dog park. This is a really hard place for pups to listen because all the other dogs are having SOOO much fun, which is why you need to be so interesting. Again, get as far away from the crowd as possible and do some work. Don't get frustrated with her as this is hard. Just give her reminders when necessary and really make a big deal out of her doing the right thing. Enlist a helper(with leashed dog) to come around her. At first they need to stay fairly far away and very slowly move closer. If she can't listen to cues with one dog walking around her, she'll never be able to listen with a million dogs milling about. If she totally loses you and goes for the dog,
immediately run away, with squeakers and excited voices if necessary. Running in the opposite direction doesn't always work--you may have to run past her, since she's already focused in that direction.
If you have a relatively slow Petsmart, then find a corner of the store or generally just a very low-traffic area and get to work. Work your way up to being there on busier days with more customers and their pets.
I've done TOOOOONS of work with Mud getting her to listen everywhere. We started in the house(low distraction---TV on, cat and one-two other dogs roaming about), then moved to the field by my house(NO distraction except that it's a new place....not for any real reason other than that it's a great place for walks), then to the backyard(all 4 dogs running about, horses a short distance away, any traffic that drove by, etc), then to a park with a moderate amount of canine/people visitors, then Petsmart. It takes a lot of time and dedication to get your dog to listen perfectly in all environments, but it's great for you and her both. So stick to it!
Glad to hear you two are doing well. Good luck! If anything is unclear feel free to ask.
