Possible GERD?

I am a 22 F living in the UK.

I've been battling gastro issues for a couple of months now and I'm trying to figure out the cause. I have been to the doctor suspecting IBS and have had tests done to rule out Coeliac Disease, Inflammatory Bowel Disease and cancer. The only thing the tests found is that I'm slightly Vitamin D deficient.

I frequently have acid reflux so now lI'm suspecting could possibly have GERD, but wanted a second opinion as my doctor isn't open untill Monday.

Here are the symptoms I have: - sour taste in mouth - abdominal and stomach discomfort that can feel likea mix of bloating, fullness and sometimes even hunger pangs even though I've just eaten. - Feling like there's something in my throat - Constipation - Passing gas (on a good day)

A hot water bottle on my stomach is one of the only things that helps to ease the discomfort. I am also taking probiotics and 20mg esomeprazol bought over the counter (have only taken them 2 days so hoping maybe tomorrow see some improvement)

Any advice would be amazing!