Feels like my upper stomach is SUPER full and I’m very uncomfortable. Could this be serious?

Hi! So basically I (26, F, 5’5, 130 pounds, no medications/conditions) have been having stomach issues for around 2 years, but they have been REALLY bad the last couple of weeks. I have this intense pressure in between my belly button and the bottom of my ribs (Google says this is the epigastric region). It’s slightly achy but mostly bloated, and just really uncomfortable pressure that kinda goes into my throat. I also have an occasional burning pain in this area, and directly above and right below my belly button (like almost the edge of it). When I feel around on my stomach, the left side in the middle near my belly button seems firmer than the other side. I’m also burping like 100’s of times a day and gassy in general, but the burps never relieve the pressure. I also sometimes feel almost like a flutter/spasm feeling in my upper right side near my ribs. I feel like I have some heart burn but rarely have anything come up. I occasionally experience constipation.

When this first started I saw a nurse practitioner at a GI office. I had labs, a stool test, a barium swallow study with small bowel follow through, and an ultrasound (I think it was upper quadrant, the results discussed gallbladder, pancreas, etc.). All of these tests were normal. Only finding was low vitamin D. I took 20mg of Pepcid once per day for 1 month and it did nothing for my symptoms.

Any advice on what to do next would be appreciated. It’s getting super uncomfortable and I’m so scared it’s something serious.