Try walking much more briskly near the end of your walk and as mentioned, don’t think about “Oh, well this is where she’s going to lay down”. Staying outside isn’t an option, YOU are the pack leader and you determine when your packs migration (Your walk) is over. If you keep thinking that she’s going to stop she’s going to sense something is wrong. With the canine nose being appx. 150 times stronger than the human, she’s completely capable of smelling your pheromones change, and this could be the cause of her stopping.
If you have to, another option is to consider running the last leg of your walk.
On a side note: Thank you for saving a Pit Bull’s Life.