First, at around 3 or 4 weeks post op, you're at the very beginning of your recovery. Laproscopic surgery is very deceiving. While your outsides haven't been affected much, your insides have been through MAJOR surgery. Things have been pulled an moved and wrapped, and stitched, and repaired. Your upper GI tract has been dramatically revised. It will take time for your body to heal and adjust. Being tired is very understandable, so as Kitt said, listen to your body, and rest when it says it's tired.
I would suspect that the reason the PPI didn't help is because the irritation is at the wrap site. At your point of recovery, the wrap is swollen, and that can cause some of the foods you eat and drink to be stopped at the wrap site. They sit there, fermenting, and waiting to go down. In the meantime they cause irritation, which mimics reflux. The esophgagus is a "dumb organ" and it interprets all pain as reflux.
Your stomach isn't accepting much because of the swelling. The fundus of the stomach (top part that was used for the wrap) is the part of the stomach that tells the brain that it's full. The brain interprets the swelling as fullness, which is why you fill up extremely quickly at this point. At your stage of recovery, I was only eating a third to at most a half a cup of food at a sitting, and maybe less. I lost 15 pounds before my stomach started accepting enough food to stop losing weight. It's very normal to lose weight during this recovery. Don't worry...you'll gradually begin to be able to eat more. Honestly, I don't remember when I could eat more normal portions, but probably around four or five months post op. It's a gradual improvement over 6 months.
Around here the rule of thumb is that it takes a full 6 months for most of the healing, and a full year for the rest. I had one quirk (occasional dumping) that lasted into the second year and then finally disappeared. I figured I'd have that one forever when one day I realized it wasn't happening any more!
Listen to your body. Surrender to your recovery, and follow it where it leads you. You can't rush this. It is as it is. Everyone is different, and yet some aspects of recovery seem universal. Glad you've found us! It's a great place to receive information and support from others who've been through what you're experiencing.
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.”