You can still grow more endo tissue even after a hysterectomy. It is less likely, but still does happen. Ibs is a pain in the ass (no pun intended). There are pills for it that do help a lot, but ultimately you just have to figure out which foods your body reacts well to and which ones you should not eat. It is different for everyone.
I also have endo and just turned 25. However, I choose to live with the pain and not have surgery. The only time that I will have surgery is when I decide that I want to have children. Then I will have the tissue cut out. They will only cut the tissue out so many times before they really pressure you into a hysterectomy. And that is just not an option for me!! Your doctor should have explained that the hysterectomy wasn't going to cure anything!!! It is possible, but not even likely.
Do not hide from the world! This has to suck big time for you. I am so sorry that you are still having problems. I would suggest getting a different doctor and taking suggestions from him/her. Good luck girls!