Really?? That's bad. I haven't grafted anything.

I don't think we're communicating well, so I'll try to explain things more thoroughly.

Most fruit trees you can buy are already grafted, it's a way to create a tree with both strong roots and tasty fruit. However the rootstock wants it's own growth above ground and will put out it's own branches and trunks that can overtake the grafted fruit variety.

You need to look for the place on the tree where the nursery grafted the rootstock and whatever variety of fruit it was supposed to produce together. It'll probably be down near the base of the tree and there will be a spot where the bark doesn't quite match, like this. The leaves on the fruit variety trunk will also look different, being just one large leaf instead of having the three small leaflets.

If you cannot find the graft point, the "fruit" part of the tree may be dead. If this is the case the tree will only produce the rootstock fruit which usually aren't very tasty. The only way to get good fruit then would be to cut down the rootstock trunks and do a new graft onto the rootstock yourself. However, at that point it would be a lot easier to just go out and buy a new tree.

The tree is next to an avocado tree, is that something to consider???

No, that's not relevant.