Fantasy. At 18 people transform into different creatures and a girl has black wings when angels only have white. 2016~2019. Spoilers.

[Satuurnn]

In the book I'm trying to recall I remember that the world took place in a sort of dystopian world where heaven and hell existed and angels came down to give people the ability to transform into other species like a werewolf. The mc and her brother would be some of the last to go through this process seeing as it was being ended. Angels were not supposed to be made through the transformation so when she transformed and had black wings instead of white people thought she marked the end of times. She ended up getting with one of the angels and another one of the angels had a child with a human and the child did not have strong wings, so she needed wings braces. Also at one point further down in the series she was kidnapped by Lucifer because he wanted her to have his children. Sorry if this is word vomit I've been trying to find this for months and I don't remember any names cuz I read it years ago. Relevant info is that I found it on Amazon as an ebook