Please take what I say with a grain of salt, because I'm no expert and have no medical training. I just wanted to share my experience on paleo, which has been somewhat similar to yours (though I don't have a diagnosis of IBS).
I came to paleo with leaky gut caused by (I believe) very strong antibiotics and an intolerance to gluten. I felt better at first eating lots of protein and fat (probably mostly due to the elimination of grains), but my digestion got worse and worse as the months passed. I am also, like you, very prone to stress. I had other problems, migraines, panic attacks, break-outs, lots of things that I thought paleo was supposed to cure. Lately I've been very concerned by the fact that my stomach seems to be rebelling... After eating a big paleo meal of fats, veggies, and protein, my stomach made horrible gurgling noises and seemed overtaxed by the burden of digestion. I took some betaine HCL supplements for a while, but stopped at some point, thinking that my diet was so perfect I shouldn't need them.
What I've noticed lately is that my "symptoms" (mood-wise and skin-wise) seem to follow periods of digestive stress EVEN THOUGH THE FOODS THEMSELVES ARE PERFECTLY PALEO. I never cheat, I don't eat eggs or dairy or nightshades. All my meat is organic and grass-fed. BUT! I would often fast for long stretches of time (as many people around here encourage IF) and then eat a gigantic bowl of stir-fried vegetables and meat. And my stomach would hurt for so long, and the next day I'd have all sorts of problems.
What I think now is that if your gut is damaged, too much protein can really screw things up. It's hard to digest. Lots of fibrous vegetables are also hard to digest. A big hearty meal is hard to digest. Supplementing with probiotics, bone broth, fermented foods, and all that stuff will probably help, but I think the best thing you can do is treat your stomach like a delicate patient. I'm moving more toward really well-cooked sweet potatoes with just a little salt and coconut oi, lots of soups and stews, and light, frequent meals rather than big hearty ones. And things have been better (though it's only been a few days so far).
I still believe in the benefit of a paleo diet, and overall paleo has made a big difference in my anxiety. But I would encourage you to start listening very carefully to your body, noting how you react to every meal, rather than trying to cover all the bases on the standard paleo menu. If a big steak makes you feel crap, avoid it for now. Don't be afraid of safe carbs if you tolerate them well. Maybe eventually you can move on to the gold-standard paleo diet, but if it's not helping you after four months, that's probably a sign that something about it is too hard on your stomach. You're still healing, so be patient and try to be as gentle with yourself as you can. Good luck.
