I echo what everyone else has said here.
For context, I adore dogs, have had dogs before, study dogs part time, volunteer with dogs, waited 10 years for Battendog.
I STILL didn't really start to love him until he was a few months old. I felt overwhelmingly responsible for him, I did every single thing I could to give him a good life, to care for his every need but it was all an investment because I didn't get anything back, in terms of love etc, until he was a bit older.
I used to say to him, "I'm doing this because one day adult-you and I will be friends". That's what I meant earlier about it being a large chunck of faith.
fwiw, my step-father is someone known as the animal whisperer and also loves dogs and spent a lot of time volunteering with wolves. When they got their JRTs, the female was such a hard nut to crack he once declared in desperation he would "give her six months" - meaning he would have to rehome her if she didn't get any easier. The pair have been virtually stuck together like glue ever since. She is a corker (if barky) of a dog but it takes time to get there.
Loads of people have those moments where they thing "what have I done?" or "life would be easier without the dog".
They are stresful and hard work, but with effort and patience it will come good.