It's early to get scared. You are still in the swelling stage. Burping is really a blessing. Many of us can't and suffer gas pains.
If you get reflux the doc may put you back on Nexium for a while. A lot of us do that for quite a long time. There is never a guarantee that ALL the reflux has been cured. At this stage you can't really tell.
Do watch your diet! You should still be on "full" liquids. Don't push it!!! Small amounts of soft foods that don't stick on the way down may be OK. Look up post-op Nissen menus if you weren't given one.
Keep a log of your foods and drinks, medicines, times, and your reactions. Find out what agrees with your new system. A lot of people have trouble with foods they tolerated before (especially beef) and can eat things they couldn't (maybe later). Don't let yourself get constipated. Meds do that! You don't want any pressure on that brand new wrap.