I do not think a 10 minute WALK is enough to tire ANY dog out!! These dogs need to RUN! To PLAY, to get all that energy out. I suspect that is the main issue. Exercise and obedience training should be done separately. You should either use those 10 minutes as obedience loose leash training, OR as a jog or run in the backyard playing fetch or letting her run off some steam.
Nowadays there are TONS of new equipment out there to help with pulling. If you dont want to use any of the equipment, keep a pocketful of treats and encourage her to stay at your side on leash by patting your thigh or using her name and treating her constantly as she is at your side. This is the "jackpot" zone and with time, the dog learns that good things happen when they stay in that area. But, this method of training probably takes the most time to train.
Also, instead of walking in straight lines, alot of people will randomly turn left, right, or about face while on their walks, as you mentioned when you notice them get to the end of the line. This basically keeps the dog on their toes and forces them to pay attention to where you are because they have no idea where they are going next. Turning the opposite direction works under the same principle that if you pull, you go a different way than where you wanted to go. But this training should also coincide with a reward once your dog comes back to you.
Next there are harnesses, front clip harnesses to be exact. The leash actually clips on the front of the harness near the breastbone, and when the dog reaches the end of the leash the pressure actually turns their body away from the direction they were pulling, effectively training them that "pulling takes me AWAY from where I wanted to go!"
They also make head halters for very strong pullers. Control the head, and you control the dog. You must be very careful with these harnesses and not jerk on the leash at all since they rest over the dogs nose and could injure them if used harshly.
You can also simply just STOP the instant the leash goes tight. Remain still until the DOG puts forth the effort to return to you and puts slack in the leash. You can use treats to reward this or just simply use moving forward as the reward. If you find the dog is mesmerized by something in the distance, you can break their concentration by calling their name, make a kissy noise, or something to call their attention back to you and make them loosen the lead.
Even though puppy is only 7 months old, she still needs alot of exercise. By replacing her bedding everytime she rips it, you are only furthering her learning how to shred things. And the more she is ABLE to do it, the more engrained in her brain the behavior will become. But I suspect that by just increasing the level of exercise she is getting, you may see the problem go away on its own as she is most likely just trying to get rid of pent up energy.
