Carrie can be a poor producer. I doubt that a pollenizer would help, but it couldn't hurt to graft another variety on to the tree. I had a Nam Doc Mai mango planted 8 feet away from my Carrie and the Nam Doc Mai fruited heavily. I never got a single fruit from the Carrie in 10 years. Some years they got to be the size of ping pong balls before they fell off. The Nam Doc Mai would sometimes fruit so heavily that I had to thin the fruit!

The answer is no! Mango trees don't need cross pollination. That being said, I've seen bees, flies and other insects pollinating my flowers. Mine are still very young, and the freeze we had in Jan killed all my blooms...almost killed my trees too. Except my container Glenn, I have a few tiny(pea) size fruits on that one.

How old is your Carrie and do you grow it in a Container or in ground? Sometimes age has a lot to do with how many fruits they have. The older/mature it gets, the more fruits you should start getting.

Here's a few info on Carrie Mango...according to this website

Here is a link that might be useful: Carrie Mango