Well these vines are well known for being slow bloomers. I had one that didn't bloom for 10 years. If the plant is happy and looks healthy, you're probably treating it well so all you can do is be patient. Do not feed it because that will encourage leafy growth and no flowers, but sadly, it's their nature to be slow bloomers. Also, if you have cold winters, it often kills potential flower buds. That's probably why mine doesn't bloom often because it's not cold enough to kill the plant, but the blooms get nailed before they develop when the temps in my garden dip below zero."