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

I have lost my enamel due to scraping it off when I was young. They break constantly and hurt periodically. They hurt so bad that it is hard for me to brush, when I do brush it seems to make the problem worse because they break even more. Most of my teeth have exposed holes, mostly at the base of the teeth. What can I do to try and keep them from breaking and allow me to brush my teeth without them breaking as well? I also really want my teeth to be white again. They are very yellow and stained.