Don't give it a second thought. These surgeons have no idea what the recovery is like. Here's hoping your surgeon ends up needing a Nissen so she can find out just how perfect she feels at 3 weeks post-op. Seriously? Seriously!
In my experience here at the forum, it's extremely common for surgeons to tell people that they'll be good to go after 2 weeks. I used to think that maybe they didn't want to scare patients away, but I'm beginning to believe that they just don't follow their patients long enough to know about their post-op struggles.
At one month post-op you are at the very beginning of your recovery journey. Really, it's very common not to be able to tolerate much food, and we all lose lots of weight. Try not to stress about it. This too will pass. Once healing has progressed your eating will return to normal and you'll gain the weight back.
I can't believe your surgeon said that there is no physical reason for you to have the problems you're having. Your upper GI tract has been completely revised, and your insides have been through a lot of trauma. All of these things will settle down and improve, but time is the only cure. You just have to give your body time to heal.
Try to relax into your recovery. Your stomach is complaining loudly now, so be careful what you put into it. Be gentle. If your discomfort is great enough, make an appointment with your GI doc and see what he/she has to say.
Hang in there. This WILL get better. One month is very early in the recovery.
We're with you!
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.”