Not yet diagnosed

At the moment I'm on the waiting list to see the gynaecologist about suspected endo. I was diagnosed with IBS but since coming off birth control I am really struggling. The only thing is my period isn't that bad I find ovulation the worst my symptoms are stomach pain, feel like I get a burning sensation near my ovaries aI always have a dull ache in my lower back I get like butt spasms loose stools and then constipated once I was in so much pain I almost passed out on the toilet... Then the week before my period the nausea is extreme I get migraine and dizziness but then when I have my period it's not to bad but then after the cycle starts again back to square one. I've had scans which came back all clear does it sound like endo i am really gonna push for the surgery when I finally see the gynaecologist but I'm so worried they will just say IBS I feel ill pretty much 3 weeks of the month it's so exhausting I've cut fizzy drinks and I'm eating a lot cleaner I walk everyday and go to the gym 3 times a week. I'm in the UK so the waiting list is monthssss and I cannot afford to go private...I've been given medication for the nausea but it wears off pretty quickly