@shafaq1233 -- Can you buy avocados at the market? It's easy to grow them from seed. The only issue is that avocados must typically cross pollinate to fruit, so the offspring grown from seed has no guarantee of fruit quality. My understanding is that some avocados have female flowers that are receptive in the morning, and others are receptive in the evening, and the male flowers release pollen in the morning or evening. So you need both kinds. But if I lived where they can be grown in ground outside, I would try anyway.
Seed grown avocados take something like 7 years to start fruiting, I believe.
Commercial growers graft branches from desirable varieties to increase them so the fruit characteristics are the same and they fruit earlier.
@sjollie - I'm hoping someone else from avocado-growing areas will respond. But as a general fruit-tree question, are the limbs breaking because the tree is fruiting too heavily? Maybe thinning the number of fruits would help?
I'm guessing your tree produces good quality fruits? Do you know what kind of avocado it is? (description of fruit might tell us if you don't know). Also, if you only have one tree, is there another in the vicinity?
(curious about the cross pollinating issue) I have heard that polyembryonic mango (multiple shoots from a single seed) can self-fertilize and have been wondering if same is true of avocados.