It looks like a type of citrange rootstock that has taken over a neglected tree. I think i see trifoliate leaves in the picture (more leaf pics would help). See if you can find singular leaves on a branch and if there is one, fruit?

The good news is that you could graft onto the rootstock if you wanted to!

Fruit from rootstock. Probably an inedible citrange and the edible grafted variety has died out.

Agree with preceding comments - you are not growing a named variety selected for dessert use but rather one that probably got on the site as a rootstock for another kind with more conventionally appealing fruits that has long since failed and disappeared. Thinking the grafted combination was a single genetic individual somebody may have even cut off a slower growing scion at some point because the rootstock sprouts that had appeared were developing so much more vigorously.

Angela, do you understand what has been explained to you? I know that it must be disappointing to know that your tree will never produce delicious fruit.

Thank you so much everyone! I really appreciate all the responses I got. It's a relief to finally know what was wrong even if there is no remedy. At least it looks nice. Thank you!

The remedy is to graft on a variety that you want and then cut away the root stock which has taken over. Read up on topworking citrus, this would grow far faster than if you were to plant a grafted orange tree.