I know that 4 and a half weeks post op seems like a lot, but you're still at the very early stages of recovery. The regurge taste you have is probably a result of the fact that your wrap isn't letting all the food go down and you're probably getting fumes. Just a guess, but that squares with my experience.
Are you taking Maalox or something like that? That would explain the stool colors. Also, you're not eating like you normally do, so there will be changes.
Keep in mind that your upper GI tract was revised and it's a big deal for your stomach. It's likely that it was a bit sensitive to begin with, and having been pulled and wrapped around the esophagus, it's got a lot of adjusting to do. The nausea isn't fun, but certainly understandable after what your stomach went through. It's still healing and adjusting to the changes.
You can have something called "dumping" intermittently as you heal, and even afterward when you irritate your wrap. At those times you'll hear gurgling, and you'll likely have diarrhea, so don't be surprised. It's not a permanent thing.
You're not going to have a normal appetite for a while now. Don't worry...once you get back to eating normally in a few months, you'll gain the weight back. This isn't a permanent problem, so don't sweat it. Try to relax and let your recovery take the lead. If you're trying to rush it or force it to go in a certain direction, it'll only frustrate you and make you feel worse. If you can accept the condition you're in for now, and let your recovery have its way, it'll be so much easier for you.
Take care, and try to relax into the process that is recovery. Your stomach has been through a lot, and the nausea is a temporary thing as it heals.
Hang in there and try to be as patient as you can.
We're here for you!