Gizzy,
I think you are doing good. I remember my puppy class trainer told us that we need to train dogs consistent and lots of repetitive for one trick or behavior training.Doing training consistently is the key,she said.
With dog,just a tiny difference makes whole different thing.If your dog leaned "Sit" inside the house and respond very well,but once you go out to yard and try to do "Sit",whole thing changes and you need to train the same thing at yard again.Plus outside has lots of distraction stuff

ther dogs,squirrels,smells,people.. so for dogs,outside and inside are complete different scenario.
With my dog,I did changing direction thing when dog starts pulling. My puppy class trainer told us to put peanut butter on tip of stick or spoon and place it next to your side(heel position area) and walk along.I tried to do this but with my dog being stumpy and I had to walk very funny so,I did walking training with different method. Changing direction when dog pulled worked for my dog.
Good luck! Oh,have you seen tv show "Its me or the dog" on animal planet?
One episode featured dog that pull very much and trainer in the show used harness that I heard from other people guessing it as "Sporn" harness.I have never used this harness so I cannot say it is good or bad but it might be interesting for you to watch this show.