What kind of tree is this?

[ilovemywillow]

I bought this tree and they were not sure what it was. It has no thorns and the leaves look like my navel orange tree.  It produced light orangeish yellow fruit the size of oranges and when I ate one that fell off the tree it tasted like a grapefruit. The flesh is not red or even pink.  Clearly grapefruit in taste.  I want to know what kind of grapefruit or orange tree this might be.  I have it in a 30 gallon pot.  Maybe its a grapefruit that just made little ones but the tree isn't overloaded. It only had 6. 

[ilovemywillow]

I did add a picture. Not sure  why it isnt showing up

[Millet]

The leaf does have the wide large petiole  of a grapefruit.

[ilovemywillow]

Can you see this photo?  It shows the small immature fruit and the leave. The petiole is not as large as the leaf but bigger than on my lemon. It looks just like my navel orange tree. I posted three different url's.  the only one that seems to work for me is the facebook link. I shared the photo as public so you dont have to be on facebook if you want to see it.

https://ibb.co/dgwLGH
https://ibb.co/nvsSwH
https://www.facebook.com/photo.php?fbid=10208971569721111&set=a.1173823920412.22047.1672477452&type=3