First let me apologize in advance if anyone who reads this is squeamish since it includes graphic descriptions of body processes. Be warned.
You say that you do have some bloating. I'm wondering whether we may be similar in some respects. I have gone to a fairly high dose with powder vitamin C (60,000 mg) and experienced cramping short of diarrhea. I was not passing all of the food I ate, though. I'm wondering whether I cramped my intestines into a pocket (diverticula) temporarily. All of a sudden after several days I passed clear fluid and food which I had eaten a couple of days before. I cant prove the fluid was ascorbic acid fluid but it seemed very sour and gave me a shiver. I just don't know whether everybody on earth follows Dr. Cathcart's Bowel Tolerance chart. It may not be the magic bullet for determining how much C to use. Just one person's opinion.
However, I'm still very enthusiastic about the megadosing with C. Everyday I learn a little more.