She is young! Focus more on the behavior than the collar. Start by not setting her up to fail. Don't let your kids walk in front of her.
The turn around method didn't work for me either. I went through 3 obedience classes and thought that I would NEVER get Bison to be alble to heel. What worked is constant reward and repetition of the position that I want him to be in on walks, formal heeling training, and especially just in the kitchen. I rewarded him for being in the right position and taught him the word for it.
Here is an activity to try...
Have a bag of treats with you. Just before she gets to the end of the leash, say "NO" and when she hits the end stop walking. It might take a few seconds for her to realize that you aren't moving. Wait for her to slack up on the leash, or even better, return to you. Say, "Yes!" and if she is in the right spot, "Good heel!" then give her a treat and start walking immediately. Repeat. Essentially, you are teaching her that if she is at the end of the leash, the walk stops, if she is in the position you want her to be in she gets treats and gets to keep walking.
To clarify, when I say "position" it doesn't have to be a formal heel position. Bison has two heel commands. "Fuss" is SchH style heeling with him exactly next to my leg with him looking at my face. "Heel" means he is within 2 foot of me on the left side and he can look or sniff or what ever he wants.
This won't happen overnight. You may have to keep this up for several weeks before it clicks with her, but you should see some improvement in a two or three sessions. If it doesn't work, try something else, but 14 weeks is way too young to use a training collar.