I have a dog who was that puppy.
I took her to a puppy play and stay..OMG she freaked.
Took her puppy classes and she coped but barely.
NEVER wanted strangers to touch her or come near ..backed away as hard as she could. Barked at every scary thing from men, men in hats, plastic bags..you name it.
Oh and velcro-d to me... you bet.
She'll be 2 in May. She has improved a great deal. She is never going to go to strangers (but I don't see that as bad..thieves would have a job grabbing her and she is not at risk of knocking over kids or old ladies!) and she does sound scary when someone knocks at the door or comes in.
BUT she has learned to settle and cope. When she became ULTRA reactive during her first season I joined the Reactive Dogs group (FB) and started following there CARE protocol (basically have your pup far enough from a scary thing that she is calm..evenif its 200m away or more... and when she sees the THING (human, dog, bag, whatever) rapid feed the best treat ever til it's out of sight..then stop. So gradually scary thing is associated with good thing. It takes time and error, and perhaps a friend with a stooge dog, but it really helps.
I am still cautious with my girl.. she now likes certain dogs..and will even play. Others get her fear reaction and we duck away, hide, change direction.. the aim is for her not to be scared... reactivity is 99% time being scared . And for her it's a slow process.. she trusts her family, her dog walker ( that was a big gamble and introduction were slow but worth it) and one friend who we introduced when she was 12 weeks old. ..that's it. But she tolerates others as long as they don't try and fuss her. And she will even settle with them in the house..after a bark fest first, and is MUCH better if we walk in with them rather than them coming in.
She sounds dreadful but she really is the most loving, funny gorgeous girl.. and CAN now run off lead with the right dogs, CAN cope with most people... she'll never be the dog that goes to strangers for a belly rub, but it's ok :)
Sorry, that was long, but intended to give you encouragement!