Beth...I had the same problem, so I caved in and bought Heather's book. I thought the diet would be too extreme to follow, and was very resistant to it until I just got so bad I couldn't stand it. Here's what I've figured out about food in the past two weeks that might help you.
1) Whole wheat triggers my stomach. Instead of D, however, I get a gurgly, uncomfortably bloated and gassy stomach. So, I started avoiding it and feel much better. 2) Dairy is a constipating trigger, too. If I MUST have it, I take a maximum dose of lactaid beforehand and then eat well for the rest of the day. 3) I definitely have problems with raw veggies. I am trying the different recipes for cooked veggies in Heather's book and am having much more luck. 4) Hot peppermint and ginger tea DO help. As does a heating pad to your belly. It helps the pain and gas. 5) And finally...I gave up caffeine, specifically, coffee. It hurt for the first week, but I think that was one of my major triggers.
Did you try to do the "what to eat when you can't eat" diet for a couple of days? As miserable as it sounds, it does settle the bloat and gas down. I think I became a believer in food as a cure after that.
Compared to the metacmucil, citracel is much, much better. I don't like taking it before I have to go out, though...I just feel a little bit bloated and full, but I think that is from the amount of liquid I take it with. I think drinking lots and lots of water helps, too...maybe really pushing the fluids will help get you started.
I hope that was a little helpful! Please write back if you have any other questions. I have to say, though, this is helping me feel a lot better, and I really do think the citracel helps keep me as regular as I can be at this point.