What should I do about my teeth breaking constantly? I also really want my teeth to be white again.

Chipping of the teeth at the neck of the tooth ( where the tooth meets the gums) can happen due to either tooth brush abrasion, from aggressive brushing habits. Or from clenshing. You need to visit a dentist to evaluate the damage that has happened to your teeth. The repair can be as simple as a bonding to restore the chipped portion and reduce sensitivity, covering the tooth with protective crowns or complete replacement of the tooth if non restorable.

Hi from Evansville, Indiana!   Sounds to me like there was a lot of aggressive brushing for a long period of time which can delete the enamel from teeth. Now you have sensitivity and chipped teeth. A short fix and the cheapest one would be bonding the teeth and stop brushing so aggressively. The boding will change the color of your teeth to a whiter shade and you will not feel the sensitivity!  Hope this helps!