I would list all your symptoms (however small they seem) and see what your GP thinks. Definitely research endometriosis and explain why you think it's possible you have it. And I would ask to be referred to a gynaecologist.
Your GP may well want to rule out other things first and/or have other ideas about what may be causing your symptoms. Unfortunately endometriosis often takes a while to get diagnosed so I do think it's worth seeing a specialist if you can (a gynaecologist will know far more about endo and other conditions in that area).
The first GP I went to wasn't worried about my symptoms at all (mainly just abnormal bleeding at this point) and tested for STI's (negative) and noted I had a cervical erosion so referred me for treatment. This did not stop the bleeding.
I went back to the same GP who tested for STIs again (still negative) and referred me for a biopsy (clear).
I decided to try another GP as I started to have painful sex (I also started having pain/bleeding with bowel movements but I was too embarrassed to say anything, which is silly). She changed my pill which improved the pain (although sex was still painful) but not the bleeding.
I moved to another area and decided to see another GP. This time I also mentioned the pain/bleeding with bowel movements and he suggested endo could be the cause. He referred me for an ultrasound (clear) and to a gynaecologist. The gynaecologist talked in depth about my symptoms and also suspected endo. I then had s diagnostic laparoscopy (keyhole surgery) and was diagnosed.
I've since had some treatment and am doing much better, but I wonder if I'd been open about ALL my symptoms and had been aware of endometriosis earlier if I could have been diagnosed earlier.
Really hope you get some answers soon, I know it can be worrying having these symptoms and not knowing why.