Welcome to HealingWell!
So how are all your meds working for you... Are you "regular" or still C? First and foremost I would suggest you take a probiotic if you're not already. Yogurt can also help you get "good bacteria" in there while keeping you regular. Dannon Activia has done wonders for a lot of us here on the boards. I have IBS-A (Alternating = fluctuating from C to D), and I keep it under control with probiotics, Activia, and a pretty healthy diet. I used to be on Zelnorm but that lost its effectiveness after a few months. Then I would stop it for a couple weeks and then go back on. I yo-yoed with it because it was the only way to keep it working for me.
Have you looked into natural laxatives like aloe vera. If you can find a good balance with it, it may be all you need for regularity. I tried the juice/gel once and it was just horrid. The consistency of it was disgusting, here on the boards we've been known to call it sludge. It's like snot. Anyway, it seems the aloe vera pills are the best. You can find them online or at most nutrition stores.
Digestive Advantage works great for some of us as well. It's pretty much a combination of good bacteria and fiber. You can find it anywhere really, most drug stores have it.
If you are prone to C then you might want to stay away from taking too much Calcium. Lots of people with IBS-D take calcium to help control their D. You might also want to stay away from bananas and dried fruits. Canned, fermented and processed foods can also cause constipation. You also need to make sure to drink plenty of water.
Eating several small meals a day means cutting back on portions. Instead of having a monster breakfast you might want to try some toast, or a bagel, oatmeal, or just eggs. Whatever you can handle in the morning that isn't going to stuff you. Then add snacks before lunch. Same goes for lunch... portion control. Eating 1 cup of food should be enough. Again, add snacks before dinner if you get hungry. I'm like a bird at work. I usually have some type of cracker just sitting out on my desk. I like pickles and yogurt too (not together!). But those are the things I snack on.
I hope that helps you some. I'm sure others will be along to give their input as well.