Hi all, i'm a 17 year old girl and i'm worried that i might have colorectal cancer.

first off, id like to preface that my family has a history of stomach/bowel issues. My mum died in 2017 of colon cancer, she had coeliac disease. My sister who i now live with has ulcerative colitis. There is some more distant family who have crohns disease.
 

i've been having really awful stomach pains, gas and cramping, and constant diarrhoea and/or constipation for a long time. I think this started in 2018, however i do have memories of this type of thing happening on and off for years prior to this. 2018 is just when it got really bad. I have always been very skinny, i'm underweight for my age. Doesn't really matter what or how much i eat, i dont gain weight. 
 

I have been for a colonoscopy, however the prep made me very violently ill and was just a horrible experience. They didn't manage to get a full look round my colon. I have also had an MRI scan on my bowel as another option instead of a colonoscopy, which was also inconclusive, they couldn't get a good enough image of my bowel.

currently i'm on the waiting list for another colonoscopy, going to be overnight in the hospital so they can give me antisickness for the prep and watch me.

I have very bad anxiety and depression, have been going to therapy for a long time. The worrying about my health on top of all my other stresses is really wearing me down.  I'm absolutely terrified of having cancer. Watching my mum die was so traumatic. I don't want to have to go through what my mother did. 
 

I'm sorry this has came out like a really pathetic vent, i'm just so worried :(