Wisteria are often a problem. My friend has had hers for 15 years and no flowers. I bought mine in flower and it has flowered every year......that is the secret.

I bought mine 10 years ago in flower and not another since!

Wisterias can take up to 7 years to produce flowers. If left to get on with it and allowed to take over a large area (35 feet high by about 15 wide) they will eventually flower, but most gardens don't have that kind of space, so training and pruning (twice a year) is best.

Info here as to how prune, and training is usually done in the first couple of years by restricting the main vertical stem or stems to 2 or 3, allowing them to grow to whatever height you want, then cutting them at that height, subsequently pruning the laterals (side shoots) as described in the link.

https://www.rhs.org.uk/advice/profile?pid=242

Poor you. Know what that like. We had one in our last house. Used to flower every year then about 6 years ago it stopped. Lovely leaves just no flowers. Didn't flower for 5 years then our last spring it started again. Never worked out why.