i wish you luck.
my suggestions are fairly basic: crate train. start working on leaving them in the crates longer and longer each day. work on mental stuff (training for new things) prior to leaving, so they’re tired, and leave them with a stuffed Kong.
i would also go back to square one with the mix you mentioned, and i would invest in a corrective collar and the training to learn how to use it properly. (corrective collars, in this case, would be Martingales and pinch collars – no full chokers.)
Work on a formal heel and reward for that specific behavior. Keep the leash short so she understands what you’re asking. In conjunction with this, I would stop dead every time she goes to the end of the lead. By continuing the walk, you’re rewarding the undesired behavior.
I am a BIG fan of tab leads for this.
I think a lot of dogs enjoy having some tension in the leash because it allows them to “zone out” on the walk and enjoy sniffing around without focusing 100% on their owner. If the owner turns or slows down it is easier for the dog to immediately feel the change in the tight leash than it is for them to suddenly hit the end of a really loose leash which probably hurts their neck. In a way this makes sense because it is impossible for anyone, dog or human, to pay attention 100% of the time (think about day dreaming in school).
There are a couple of tricks you can try. One is to train the dog to walk on 2 different pieces of equipment. For example, if they have a buckle collar on they must keep a loose leash at all times (could be used for busy sidewalks, vet visits, ect) and if they have a harness on it means you are on a more casual walk and you don’t mind them leaning on the leash as long as they aren’t yanking your arm out of socket. You could also use different commands (“heel”- walk at attention by my side and “walk on”- we are just walking for enjoyment so slight pulling or sniffing around is fine). One thing nice about using commands is that you can alternate during a walk. For example, you can practice “heel” every time you cross a street and then allow the dog walk casually during the rest of the walk. Your dog will give you better attention during the heel because they know it will be over soon, as opposed to you trying to demand perfect focus for the whole walk.
If you want the dog to always walk on a loose leash when wearing its buckle collar, make sure you only put that collar on when you are mentally ready to train and have sufficient time. Don’t use it during quick walks around the block before work when you are distracted/ in a hurry and not paying attention. Start out by having the dog practice sitting for you a few times indoors for a treat. Proceed outside and as soon as you feel tension on the leash stop and wait! Don’t move at all, it helps to have your hands holding the leash at your waist so you don’t accidentally give more slack when the dog pulls. Wait for your dog to sit automatically (without a command), then give a treat, and take one step forwards. A lot of dogs will explode to the end of the leash with excitement so be ready to stop and wait again. Allow the dog to pull, jump up, bark, paw you, ect without punishment. Just wait for the sit, give a treat when they sit, and walk forwards. See how many steps you can take on a slack leash. When the leash is tight, stop and wait for the sit again. Soon the dog will be really focused on you because they are ready to sit every time you stop. Once you begin walking along on a loose leash, you can periodically reward the dog with a piece of kibble for looking up at you. Remember, reward the dog when it does something you like.
Sophia Yin has some great training videos related to this on YouTube!
https://www.youtube.com/watch?v=Z2vZusiOzJg
https://www.youtube.com/watch?v=EUCl6ndLN7Q
https://drsophiayin.com/philosophy/
Ian Dunbar also has a variety of great videos on this subject.
https://www.youtube.com/watch?v=U92mG5-V26M
https://www.youtube.com/watch?v=dkapxaexrBA
https://www.youtube.com/watch?v=fLERx9XR8pU
https://www.youtube.com/watch?v=InJD18Zxudc
https://www.youtube.com/watch?v=Saa13XvCdlI
http://www.dogstardaily.com/book/export/html/2131
I also recommend Grisha Stewart’s book “Behavior Adjustment Training”.