Wisteria questions

I bought a house last year with 2 very large wisteria growing on an archway. My question is why is it not blooming?? It did not bloom last year and it has leafed out fully now, started about 3 weeks ago.
It is pulling the archway to one side because of the weight I suppose. Is it a pruning problem, fertilizer or what?
Will appreciate all help. I researched the plant files here and it is a chinese wisteria. Don't know anymore as it has not bloomed.

Do you know if it bloomed for the previous owners? If it's never bloomed, there are a couple possibilities: 1) they grew it from seed--when you do that, the plant can take many, many years before it blooms, or 2) not enough sun in that particular location. If it's bloomed before but isn't blooming for you now, then my lead suspects would be 1) it was pruned too much last fall, and since it blooms on old wood that means it won't bloom this year, or 2) too much nitrogen fertilizer, this will stimulate lots of green growth but not so many flowers (Wisteria, especially the Asian varieties, are pretty vigorous growers anyway, I never fertilized the one I had at my old house and it always bloomed fine)