Certified GKH Gardening Expert
That appears to be quite large of a container. Going up too large, too fast, will keep it from fruiting for several years. In order to fruit properly, they prefer to be root bound and well established. It may be a couple of years before you see fruit from it, at least until the roots have time to fill out that container.
Another thing that can affect fruiting will be the ratio of fertilizers. The best thing will be a fertilizer designed for citrus until you are familiar with mixing your own for the correct NPK ratios. This should be applied regularly, since they are heavy feeders.
The soil pH needs to be a little on the acidic side. 5 to 6.5 will be best. They will change the pH of their soil quite frequently, so it is best to check frequently.
Last, humidity could be at play here. Lack of humidity will keep flowers from forming. You may try to spray the tree often, if this is the case.
Here are some articles that will help: