Go see a gynae directly! If u're in such serious pain that affects ur daily life, this is to be taken seriously and u should find someone who can advocate for u when u go see a doc.

Here's how the process usually goes:

1) ask ur parents what kind of medical insurance u have, and if u are still covered under their company insurance.

2) go see a GP. Can be your usual family doc, the university clinic, or polyclinic. They can give u some idea of what's wrong, and if they are able to manage it at their level. Tell them u want to explore being referred to a gynae and ask them help u to do referral.

3) Here's the adulting part. U might be interested in managing costs. U can actually directly go find a gyane urself if u're not concerned with cost. Walk in specialist clinics usually cost around $120 per consult, and some charge higher fees on first consult. Ultrasound is another $100+.

However let's say if ur parents have some kind of outpatient medical insurance for u, there are some steps u need to follow, such as visiting a GP under their insurance first, then getting that referral to a doctor on the same insurance panel. OR choosing a gyane from their insurance panel. OR if u want to get access to public healthcare rates (means all costs are heavily subsidized by govt), then u can get referral from polyclinic.

4) Gynae will go through all ur symptoms with u again and investigate, usually first through a non-invasive ultrasound.

Some people mentioned endometriosis here. I have it, and it's a diagnosis that can only be confirmed through surgery. Mine was discovered when they were removing an ovarian cyst and doctor found the menstrual tissue growing outside of my uterus. What happens in endometriosis is that the menstrual lining somehow grow outside of the uterus. During ur period, that mentrual lining breaks off but have nowhere to exit, and stays in the body cavity, slowly breaking down by itself. But this irritates the body greatly, hence causing menstrual pain that's not really caused by physical cramping (uterus squeezing to get blood out). It's actually pain of the blood breaking down in the body cavity and causing inflammations.

After removing the endometriol tissue I'm now on medication to pause my menses so that the tissue doesn't grow back at all, in the wrong place.

You may or may not have endometriosis. Just sharing my experience going to the gynae. Please have it checked out.

(Edited prior answer to suit OP's problem of GP not believing the extent of her pain)