I have this problem as well. I can't really tell when I'm full. If I don't actively watch my eating, I can eat all day long. When I don't have much time or when I eat in between activities, like not dining with others at the table, I eat really, really fast. Something I picked up in the military (maybe) I always tell myself.
Aspies do have sensory issues. People with more severe, (almost) non-functional autism, have to be told to stop eating otherwise they keep on stuffing and end up littering themselves. It could have something to do with a precursor of diabetes, borderline diabetes (I had my glucose level checked and it was fine)(also fast eating is a sign). Autonomic neuropathy, also associated with diabetes, can cause digestive problems.
Since a few months I really have digestive problems. I've been constipated a few times because I ate too much and an insane amount of fibers, nuts and "healthy" fat. Now I'm seeing a doctor because I have stomach problems: pain (dyspepsia), constant fullness, GERD and really bad breath (at times). I'm on medication for it. It's getting better, but slowly and I have to really watch what and how much I eat.
So, besides being the mental aspie, I'm also experiencing the physical down side of that part of my life at the moment. I'm confident that the latter will go away. Because of all the digging to find root causes for my problems I'm almost starting to think I'm hypochondriac. 