Welcome to the Healing Well Wrapped Club! Don't worry...you're not always going to feel as badly as you do right now! You're at the three month point in a healing process that takes a full 6 months for the majority of healing to occur, and a year for the rest.
It's very common for post-Nissen patients to feel well and progress just fine until they start eating a larger variety of normal foods. It's easy to forget to continue to take small bites and chew, chew, chew, and some foods can irriate the wrap.
You are right that if you're getting some of what you're eating and drinking(or even medications)held up at the wrap site it can create irritation that mimics reflux. It's also possible to actually get reflux, as a Nissen is only aimed at creating a "normal" amount of reflux (everyone gets some--just not GERD levels). If the surgeon created a wrap that allowed zero reflux, you wouldn't be able to get food into your stomach.
Relax. Surrender to your recovery and follow its lead. If your stomach is rebelling against what you're putting into it, back off and stick to easier, less stressful foods. After it's had a time to heal and get feeling better you can begin to introduce that fun stuff back into your diet. Listen to your body. It'll tell you what you can and can't do.
The thing is...it's a laproscopic procedure and your outsides heal very quickly. It's easy to forget that your insides underwent MAJOR surgery and still have a lot of healing and adjusting to do. You can't rush this process. Really, you don't want your surgeon to mess with you during this healing process if you don't have to. Let your body heal in its own time...you can't rush it.
Don't worry about the coughing. Believe me, you couldn't have been coughing more than I was. I had a lung infection both before, during, and after my surgery, and also have asthma. I coughed severely throughout the first two and a half months of recovery. In addition to that, my internal tissue was very fragile because of the steroid use that was necessary prior to surgery. My wrap weathered the storm and remained intact. I understand the worry, as I had it as well, but as I proved, the wrap repair is very strong.
The one thing you DON'T want to do is vomit, or even retch, so be sure that your doc gives you a script for anti nausea medication and always keep it handy, just in case. That is one thing that can cause wrap problems.
Good luck! This will get better...just baby that stomach and wrap for a while.
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”