I never brushed my teeth when I was a kid?

Please don't give rude answers. I know it's gross. My parents never really forced me to brush my teeth when I was little. I've only started brushing 3 years ago when I turned 13. And even then, I haven't brushed properly until about last year. I went to the dentist, and he said that I have about 14 cavities. I hate my teeth. They are disgusting. I'm brushing almost 4 times a day now because I'm so worried people will notice. My teeth are yellowish.. I'm really ashamed. My teeth have been starting to hurt so much. My gums bleed whenever I brush my teeth, and I can't eat anything too cold or hot or my teeth will hurt like hell. I used to eat SO much candy when I was little. I am regretting it now. No one told me how to eat healthy or take care of myself. I'm really trying to change now, but I'm very worried about my teeth. They've been hurting so much lately. I feel like brushing and flossing isn't enough. What should I do? Is there any hope for my teeth? I know they'll be okay in appearance because my teeth are perfectly straight, and I'm planning on getting them whitened when I'm older.. but my teeth are really messed up. They hurt so much. Will the dentist be able to fix my teeth so they can be normal? I seriously have black holes in my teeth. I'm so worried..