My knee-jerk response is that your tree has not bloomed/fruited because it's grown from seed (one online source claims at least 10 years from seed to fruit). Any little 5-gallon grafted avocado would have bloomed/fruited it's first year in the ground. Of the two potted trees I have, one is only about 1/2 inch in diameter, but still flowers profusely each spring.

So although I don't have any experience gardening in Yuma, my guess is that the climate is not what's inhibiting your success with avocado, but rather the particular plant you have. According to the literature, whatever avocadoes a seed-grown plant might produce will not necessarily be very tasty either.

I would just go spend the $25 for a nice 5-gallon avocado from Lowes or Home Depot. You also might look into grafting some good varieties onto the branches of your existing tree.