You sound a lot like me. I was born with severe GERD and I had severe delay in stomach emptying. Like you, I was throwing up everything, and my food would even spoil in my stomach before it could even be digested. Naturally, the only option for me was the Nissan, especially since the meds wouldn't work. Since I was 10 at the time, it took awhile for my doctor to become comfortable with the idea of surgery. Finally they decided to actually agree to doing it and they decided that at the same time when they would do the nissan they would do a pyloroplasty too, which fixes the stomach emptying problem.
This is NOT common at all but I do want to give you a heads up about how my body reacted to the surgery. After surgery, my body was basically shutting down on itself and doctors didn't know why. My body was rejecting all food or drink, even from the feeding tube they put in when they did surgery. I had a really hard time recovering, and I was really sick for over a year and it took me a couple years before I could eat almost normal again. Everyone reacts differently to surgery, and I don't want to scare you about it because I was not a typical patient whatsoever. Now, I am thankful that I had it done and have not experienced problems related to GERD since surgery. I have still contineued to have other GI problems though, such as having my gallbladder removed, and now the doctors are thinking I might have Crohn's disease. Throwing up everyday is not fun and I can relate completely to your situation. Keep your head up, your doctor knows what they are doing and if you feel differently then you can always get a second opinion. Trust me, you don't want surgery if you don't have to have it, and if there is a medication out there that will help you feel better, then it is worth exhausting all of your options before you resort to having major surgery and getting a major scar since most surgeons don't feel comfortable doing a nissan laprooscopically on children. Just have faith that this will eventually get better one way or another :)