Some folks who have recently completed their earth ovens are often a little discouraged because they really don't know how to bake in them. You need to practice, and you definitely need to get your oven hot, really hot for pizzas.
How hot? The oven floor where you'll be baking should be about 650 degrees. How will you know the temperature? Well, easiest way is with an infrared thermometer with laser. I bought a Mastercool from Amazon for about $35.00, and they even give you a case and a dial thermometer.
Of course, there is the low-tech way. You could toss some flour on the floor and observe how long it takes to turn brown, or ask the person who you live with to reach into the oven and calculate how many seconds it takes before you hear a scream.
If your oven is not hot and fiery, your pizzas will not bake properly.