YA novel: girl in a bank robbery creates many short groundhogs day style time loops to survive/save others

A YA novel that was Hardback in about 2016, but could be older, gotten from the library. It was in English.

The story was about a girl, I believe in foster care or otherwise without involved parental figures. She had the ability to create time loops, in a way. She could go back in time about ten or 21 minutes a set number of times, and once she'd done it that many times (10? 15?) she couldn't time travel to any time within that window again.

She was in a bank that had big windows in the front. I remember she noted that a woman with a baby carriage/stroller was nearby. someone tries to rob the bank and she jumps back in time. I think she called it something particular, but can't recall what exactly. she could take her clothing, but nothing else. I believe that once she triggers her time looping, she can't stop until she's done it all X times, but that could be wrong.

she tries just not going into the bank, but I think that gets the baby in the carriage shot.

she also notes that someone else in the bank, a cute guy about 20, also has a gun. she wastes some time loops trying to figure out if he's safe, and then trying to convince him she's really in a time loop. he turns out to be a PI or a cop, and in one loop he gives her a password to 'prove' to him in her next loop.

in each loop except the last one, the robbers kill people. I think in the last one the girl is shot but not fatally. the PI/Cop dude promises to help her, and she wants to pursue him romantically but there's an age gab so ether he turns her down or she internally decides to wait a few years and doesn't bring it up? (she's no older than 16, so ... yeah)

I don't remember what the cover looked like, but it was a about 200 pages. I don't remember what any of the characters were named or described as looking like, but a small part of me thinks the girl might have been black with braids?