I'm baking on a pizza stone that I preheat at the max temp my oven goes to, using the broiler for the last 5 minutes. What makes you say there's not enough bottom heat?
This has got me drooling, looks delicious. Well done indeed!
I like to do a double bake of my pizza - first bake without the toppings to make the base. Then I add toppings and bake again until the cheese melts. Don't use the broiler in my case.