Did you meet her parents? What where their temperaments like?
You can’t reinforce her fear but it’s better not to put her in situations that make her fearful. If you go at her pace her confidence will increase and she’s more likely to want to explore more. There is some good advice on a current Doghouse thread about things that can be done to socialise your dog and build their confidence and resilience, some from the safety of your own home:
“Socialisation is also way more than just visual.
Think of surfaces they need to walk on - this can be done at home, so get wooden planks, thick carpet, laminate, a trampoline (obviously wit you holding on!) surfaces that move .
Smell is very important, barbecues, petrol stations, smoke, animal smells.
Sound play sounds on phones squawking birds, gunshots, fireworks etc
Put novel items in the house and garden, wheelbarrow upside down, ironing boards on their side, plastic bags (supervised) blowing in the wind in the garden.
REMEMBER all of this should be under threshold and watch out for your puppies reactions, any lip licking, yawning, turning head away, ear position, whale eyes, panting etc increase you distance.”
In my experience, adult collies tend to pull a lot and are strong on the lead. Do you have a backup plan if she becomes too much for you to handle? Is your husband prepared to do all the walking and training?