I hold in poop causing constipation?! Please help?! Am I going to die?!

I'm constipated with the same poop in my body for about a month now and I feel like Im going to have a short life. I was also constipated for two years but this time period was the worst. My belly has gotten huge. There wasn't once during these two years when there wasnt any poop in my body. It has nothing to do with my diet. I think the cause of it was because I used to hold it in when I was little then I've gotten used to it. I regret it. I'm scared I'll have cancer in the future. My parents don't care about me and thinks that it's just normal constipation and will eventually go away. Bit I haven't experienced any symptoms or pain during these past few years. I've almost tried everything, laxatives enema metamucil bit they only help a little. Not all of my poop comes out all together there is always some poop left in. but I can't get it out.