Don't give up. There are too many nay-sayers out there who will try to discourage you. Don't listen to them. The only one who can make you give up is yourself. ↗
And if doctor says that you don't have IBS with constipation, you might want to get a second opinion, because I had doctors that were telling me... of course, a lot of this has to do with science - progressing. ↗