Possible Intestinal Dilation? Get help?

Since I was a child, I have disliked defecating, possibly from a traumatic event. Besides the point, I would hold in any urge to the point of needing an enema so I wouldn't need to be hospitalized. This went on until I was about 15 (10 years I would estimate) which is when I then took it into my own hands and began to handle it myself. ButStill not on a normal schedule. I wouldn't defecate for a month or two, then I would have a couple of days where I would do it excessively and "clean myself out". I am sure that when I was younger I had made it 6 months without defecating. I am now 20 and I still only defecate every couple weeks on average, it just depends when I can actually remember that it is a bodily function. So! I have: lost all sensation of having to go, I also cannot fully empty what I can feel in my rectum, no matter how hard I try, which is problematic. I am also oddly heavy for my physique. About 20-30pounds above a friend of very similar body physique, should I get help?