I learned a lot fostering a 1 yr old pit bull who was terrified of everything!!
Sounds like Sadie is going through a fear period, which is common at her age. For her, I would suggest carrying some cut up hot dogs with you. When something scares her, toss pieces on the ground around her, but try not to let her see you do it.
In her little mind, it's "Every time I see helicopters (or whatever) hot dogs fall from the sky!! Helicopters must be good things!"