I need to find a book

[hex1686]

Hello, I registered on this site because I've scoured the internet for hours in search of a book that I know exists but has no traces. It is science fiction. It starts out on a spaceship, the female main characters father is from Earth or a planet and he came to the space tribe ship and had a daughter with one of the women of the ship. People that live on space ships are pale white from generations of living without sun, but the main character due to her father has tanner skin. Per tradition another space tribe ship comes and everyone believes she will be married to the son of the other captain. So she gets close with this son and they end up making love in the ships lake or something and are caught. It turns out she was meant for the other ships captain even though he has many wives. I think they end up deciding to kill her and the other ships captain is angry and they leave and he intends to punish or kill his son. Likewise the captain of her ship I think decided to kill her, they bring her to a room and try to suffocate her to death or something by draining the air, but during the time she figures out how to breath some liquid or something some fish or something live in that has oxygen of some kind. Eventually she survives and somehow gets off the ship and I don't really know what happens between, but she ends up on a trash island on Earth and gets taken in and helped by a mother and daughter, they bond over time and eventually a storm destroys the island and the mother dies, but in a small ship the main character saves the girl and they get away. I think they make it to another planet at some point and they somehow find the main characters grandmother, and she takes them both in. They go to school and the younger girl learns and adapts very quickly but the girl from the ship fails badly and gets in with the wrong sort/ so says her grandmother or something. Then I don't remember much, but she leaves and I remember the ending to the first or second book she runs into someone from her or the other captains sons ship and she says things are different, and things are more fair for women on the ship now. (I probably got many details wrong, but I'm going mad, I know this book/series exists, but I can't find a trace of it on any book site or on the internet itself.)