i can see why you're worried about breast cancer, just because your mom and her sister had it young. They're risk factors and it just means it's good to follow it closely. Was your breast cyst big enough that you could feel it? did it go down? Or hasn't gotten bigger? near and around menopause there can be benign cysts that come and go. Glad your doctor thought it was fine.
My best friend since grade school, age 10, we're 66 now, was having close frequent follow ups for breast cancer because her younger sister had it. Her sister had a lumpectomy. It's been many years since then and her sister is still OK. About 3+ years ago, my friend got diagnosed with breast cancer, no evidence of spread to lymph glands, localized, but she elected to have a total mastectomy. She wanted to minimize her chances of getting it again. She also chose to have chemo. She's been doing good. She does various health things, not a lot but she is making gradual lifestyle changes in that direction. She continues to have regular pretty frequent visits with her breast doctor. She also sees her oncologist and they do periodic scans, but she is on her way to being pronouced cured. She had reconstructive breast surgery and that looks good.
Hopefully you can follow the breasts closely so that if you did get cancer, it would be early and successfully treatable. My friend said the type she had is some really aggressive kind, so it's good that she has been on top of monitoring it and caught it when it showed up early.
As for the liver, the liver is usually painless. Symptoms of pain are usually thought to be related to the gall bladder. i believe that usually the only way the liver has pain is if it has some kind of advanced cancer or cirrhosis. Your ultrasound seems to rule out any advanced liver disease, although i'm not sure about cirrhosis, but with that there should be blood tests showing abnormal liver related results. You can ask your doctor about that.
i can understand the back and stomach pain worrying you. Both back and stomach pain are so nonspecific, they can be caused by so many things, a lot of which are never discovered and eventually they go away, but i understand wanting to find out what it is.
I hope you have a good time. It's natural to worry, but hopefully there would be things to distract you and make you happy. You're probably fine. i know what it's like to have scary symptoms and no explanation, and i have worried a lot about those things. Eventually it was all figured out, but it's hard to not know what's going on. Talking to a radiologist or someone who can give you more information sounds like a good idea.