What's the Name of That Book??? discussion

I am trying to help my daughter find a book she read in ninth grade, so late 2014 or early 2015. She says it was fairly new at the time, but at least two books in the series were already out, so probably before 2015.

First book reads like realistic fiction and then at some point the girl discovers something about herself - like she can turn back time or has a magic twin are examples but not actually it. Then in the second book she finds others like herself.

The book series titles were connected in some way - followed a pattern like sharing a a prefix (un- or dis-?) or root word (time or clock?) or suffix (-less?).

Covers are a black background and show a caucasian girl with brown hair. She is the only picture on the cover. Text is white.

Books are relatively short - 200-300 pages. Books were found in a (typical to conservative) high school library.

We already know it is NOT:

The Lynburn Legacy (titles Unspoken, Untold, Unmade)

Unwanted (sequel Hunted)

Unwind Dystology

Clockwise Series (Clockwise, Clockwiser, Like Clockwork, Counter Clockwise) my daughter says these covers are closest to what she remembers

Thanks for the help!

I found it! The first book is Pivot Point and the sequel is Split Second