To be honest it was quite the opposite you experienced with Pheobe. Because Millie had never really been out at all (spent her first 10 months in a small garden running in circles

tearing up the lawn running the same route

)and was 10 months old she was slightly 'mental'

Had so much inbuilt energy, she didnt understand that walks were a bonding / pleasent experience and was so crazy at being outside she was oblivious to us.
Honestly I came hoe in tears so many times

So angry with myself for letting Millie play up! So frustrated we seemed to be going back wards, it really was one step forward two steps back at one point.
We spent a good 6 months walking with head control (Which I didnt like but my shoulder couldnt cope with her strength!), practising sitting at roads to slow her / get concentration, walking past different situations took a while. I had to get her to sit every time we were to pass another dog / horse etc to teach her she cant charge forward like a loon.
I reckon it took a good year before we had the completely chilled / relaxed dog who trots along with no pulling forwards / backwards / sideways and will confidently walk past other animals without rying to say hello without permission.
You mentioned seeing a local trainer - This sounds like it could be a good idea. Maybe ring a few and ask about techniques (To avoid any whom you arnt happy with) and ask if they have seen this behaviour before. To have the support of someone who has experience of this could be really beneficial.
It's such a shame her breeder didnt help her with this when she was a wee one
You will get there though and youl be be giggling about it one day!! (Sorry this response turned into an essay!!- I always babble on when im talking about the pain in the bottam Millie was when she was younger!)