I'd first ditch the choker. 5 months old is still soooo young to be expecting much from her, and I've never seen a choker stop a dog from pulling.
I think you might find the "choose to heel" game beneficial. Basically it teaches the dog that being at your side is the most awesome thing ever, and they are choosing to be there on their own because it requires you to do nothing except walk around. I start this in my backyard with the dog off leash. I just walk around, and anytime the dog catches up to me and is at my side, I click and treat (if you don't use a clicker you can just say Yes! or Good!). And if they maintain that position as we're walking, I keep clicking/treating. Dog gets sidetracked and slows down or wanders off, that's fine. I either change direction or speed up, maybe pat my leg to get their attention if they're really in their own world. Usually a direction change or change of pace is enough to get them interested and run back to you. And again, always clicking/treating for them finding and maintaining that position that we want. When the dog seems to be "getting" it, then I'll throw in some turns, where I expect the dog to turn with me. I find the dog gets it better if you start out turning INTO them.
When we're good in the backyard, I move to somewhere like an open, empty park. Little more distracting than the backyard because it's a new environment, but not crazy enough that there's much else for your dog to focus on. And then I just do the same thing. Walk around, c/t for finding and maintaining position (and I use a leash here, btw, just for safety).
Then we progress to a "real" walk around the neighborhood, and at this point the dog is pretty familiar with the game and knows that being at your side is what gets them rewarded. It doesn't take long to get to this point. I think with Juno we worked in the backyard once, at the park once, and then we went for a walk and it was the most enjoyable walk I've ever been on with her (I still click and treat at this point). She was giving me heads-up attention and when she did start straying a little too far ahead, she knew it and would self-correct, and slow down back to my side.
Also agree with althea, don't let her pull on walks. Stop walking or change directions, but don't continue moving forward when she pulls.