Digestive enzymes
It takes time, but your digestion should eventually return to normal. You will always need more fluid (2 litres per day) than a "normal" person, though. As my surgeon explained it, before surgery your stomach would hold a certain amount of fluid in reserve that your body could draw on when necessary. But WLS removes that portion of the stomach; hence the need for more fluid.
I assume you're taking citrucel for constipation. One thing I learned from a pharmacist is that medications for constipation won't work if you don't drink enough fluid. After learning that, I found that I could usually "fix" constipation by simply drinking extra water. I really learned this lesson when I got my first blood work done. I needed to drink 1.5 litres of water in about an hour so that my veins would swell up enough for them to be able to take the blood. That cured my constipation! Also, I felt so good from the extra hydration.
In my case, I think I was off the anti-constipation meds after about a month. I had frequent problems with constipation before surgery, and I still do now, but I can usually solve it with more water; I rarely need medication. Although I was able to get off the constipation meds at about a month, everyone is different. You may need longer.
How much fluid are you getting in? Even if you're getting your 2 litres, you may want to drink even more water. Some people on the forum have found that they need 2 1/2 litres.
I just started taking a digestive enzyme (1 capsule twice a day) with the goal being to eliminate or at least decrease gas. I don't get bloated but my farts are pretty much toxic at this point. Whatever you are imagining it's worse. I was doing Devrom but it didn't seem to help me much despite taking up to 8 of them per day. I think the digestive enzymes are helping a bit. Just gotta take them regularly.
For me, I discovered that if I kept oatmeal as a breakfast staple it helped me keep my #2s good and it was processed well and has great health benefits. I usually do an oatmeal packet, a banana and a pure protein bar for breakfast. I could easily eat more but I cap it there. Constipation post surgery is no joke. I'll do do whatever it takes to avoid it. Hope this helps.
+1 for oatmeal!
Another thing I find very helpful is milled flaxseed (linseed). I forgot to mention it because the main reason I take it is for the omega 3, but it's also good for constipation. I have it every day, usually in oatmeal, but sometimes in hot drinks. I use about a tablespoon daily.
If you're not currently constipated, maybe just try a teaspoon at first to see how your body reacts. If you're already constipated, maybe try a tablespoon.
I make sure I take magnesium everyday. It takes care of constipation problems for me.
The excessive farting is probably from artificial sweeteners. I found out the chewable vitamins I was taking were sweetened with maltitol. Check labels on everything you are eating and drinking.
Real life begins where your comfort zone ends