Is it normal to have three wet dreams in one week?
Yes, it is perfectly normal, especially in your adolescent years. You have wet dreams when your seminal vesicles get close to full. But the rate they produce semen varies with how often you get aroused and your hormone levels.
Your body is a complex mechanism and you are changing. That means the levels of hormones and everything else your body controls have to be constantly adjusted. There are going to be periods when too much of one thing or another will be produced -- including your sex hormones. When that happens, you get an over abundance of semen for a while until things settle back down.
What's the best way I can control sexual desire? I get aroused a lot and it's hard to think straight and resist!
Consider this practice in exercising self-control before you are faced with really difficult temptations.
The best thing to do is distract yourself with practical matters. It gets too distracting, you will very likely be able to trigger an ejaculation without resorting to lustful thoughts very easily. Otherwise, you will probably end up having a wet dream that night. You can "encourage" the wet dream to happen by sleeping in the nude. Once an ejaculation happens the sexual desire will decrease for a while.