cindee.....cindee...cindee.... :(
I have news for you..... I'm 117lbs and 5' 8" tall. I'm no body builder and have (self admitted) very little upper body strength. (can't do even one push-up.

) Strength has nothing to do with moving your dog. Respect has everything to do with it. Manners have everything to do with it. Training.....has everything to do with it.
Your dog.....doesn't do what you would like him to do...because he DOESN'T HAVE TO. You've done an outstanding job conditioning him that if he doesn't wanna; he doesn't have to because you won't reinforce anything you say. It's quite simple in his mind....and he's RIGHT.
"Prong collar didn't work". BS. They DO work; 100% of the time if they are used correctly and by someone who knows what they're doing. When they are used correctly; they are a SELF CORRECTING training tool....YOU don't even have to do the work..the DOG receives the correction when HE to not strain against the lead. The only time they fail is when the human end of the lead fails. Period. (That's right folks.....I did go way out on that limb and say THEY WORK 100% of the time and I'll stand by that 110%.)
Toughen up means.....HE'S A DOG.....You are not. It's HIS JOB to live by the rules of the HUMAN.....not the other way around.
A trainer is an excellent idea.....and please... lose the "I'm a fragile female who owns a strong dog" thing........ Learn how to handle your dog and you can work a 240lb intact male Mastiff around 10 bitches in season.