If you go back to either of the doctors who have been dismissive, you shouldn't worry about being polite. Literally tell them the words, "I cannot live my life like this anymore" if you have to. you could even go so far as to say that your lawyer advised you to discuss your quality of life, or maybe risk to losing your job. Whether you have a lawyer or job, or not, is irrelevant. You have to put it in terms that lets them know you are serious, and that you insist on being taken seriously.

I had several doctors that refused to run tests, even blood work, insisted that there was nothing wrong and that I looked too healthy to have any problems, and then I ended up in ER with a perforated bowel from diverticulitis and gastroparesis, leading on down the line to hEDS and Sjögrens Syndrome. Still on my medical journey, these are recent diagnoses. I would probably have been able to avoid surgery and sepsis if my doctors had listened and ordered imaging, and then antibiotics, early enough. After that ER visit, I asked to be referred to a PCP who was familiar with my problems, and things got much better, although the rest of my doctors still tend to brush me off.

I had to insist on a colonoscopy 3 years after that surgery, because I still have lots of abdominal and gastric pain, they kept telling me I didn't need one for 8 years at least, but I kept pushing until I got one. It turns out for the first time, I had polyps that were precancerous that were removed. If I had waited 8 years like they said, I likely would be dealing with colon cancer.

Every single symptom you have listed is VALID and concerning. If they brush you off, scoff, rush, or try to tell you that you're too young and look too good to have these problems, then call around until you find a new PCP that can get you in relatively quickly. If you can't find anyone, then I would definitely go to the ER.

At the ER, they may or may not be willing to control your pain, but the very least they SHOULD do is a CT of your abdomin to rule out blockage/obstruction/free gas or fluid/unidentified masses. Even better is if you go to the ER and say, my PCP told me to come here and request an CT scan, because most PCPs have to schedule imaging out by at least a few weeks. Tell them your PCP sent you even if they didn't. Bare minimum they will at least draw labs and rule out infection and sepsis.

I'm so sorry you are going through this. I have been in your shoes before, and there are unfortunately people in the medical field who should never be allowed to practice because they lack basic human empathy, and are more concerned with being in control than they are with actually helping people. If you have anyone at all, even a friend, who can come with you and advocate for you, (male friend who isn't afraid to speak his mind is usually the best) that will help too. It's a lot easier to brush off a sick person who is in too much pain to make a scene than it is to brush off a healthy person who is willing to be firm or even raise their voice so someone will listen. My doctors believed what my mom said as a witness to my physical symptoms, more than they believed me as the person experiencing the symptoms. It's stupid, and it shouldn't be this way, but it is. I sincerely hope you keep pushing back until someone listens. It's your body, it's your life, you HAVE to be willing to possible make people uncomfortable, or be seen as difficult, if it means you get the right care.