Hey, come here. -hug- I was where you are when I was 14/15 too. We'll go through this one at a time, okay? Firstly, take a deep breath.
Ovarian, lung, and colon cancer do not happen to people your age without a family history. Lung cancer usually happens to life long smokers, or people who work in industries with chemicals and stuff for years and years. Bone cancer and leukemia can, but very, very very rarely, and with very obvious symptoms. You would not be questioning whether something was wrong if you had one of those. You'd know.
I have had joint pain since I was very young, but it stopped once I stopped growing. It's entirely possible that's just growing pains or something like that.
I also have had acid reflux my whole life. It's the anxiety. Trust me. So's the other bathroom stuff. It could be IBS which is annoying, but not deadly, and made worse by anxiety.
Anxiety will cause weight loss, sleeping more, and weakness. It takes a lot of energy to be that scared all the time!
I don't think you need to worry about the x-rays and CT scan. As long as you don't have them really frequently, way more than you have, I don't think they'll hurt you.
You can trust your family. They would have caught it at the hospital and in blood tests, especially something like bone cancer or leukemia.
Again, the weight loss is anxiety and depression. I lost a ton of weight when I was really bad because I was too scared to eat, and didn't notice I wasn't eating. So then I got scared about the weight loss, and the cycle continued.
Skin cancer doesn't cause rashes, either.
It's really important you breath and try to let the logical side of your brain hear me. It's really easy to let the anxiety part take hold, but you have to try. I didn't think I could, but I'm doing so much better than I was even a year ago. Last summer, I'd cry for hours thinking I had colon cancer. I don't. I see that now, but sometimes my anxiety still scares me. But I just take some deep breaths, relax, and think it through logically. It's hard, it'll take practice, but you can do it. It's really good you're aware of your anxiety and want to get better at this age. It gets harder to shake as you get older, like any old habit. I believe in you, though. You can do it. <3