I seem to remember them explicitly testing Caitlin for meta-human-ness after they found out about Killer Frost and the tests came back negative. If that is true then she never would have gotten powers without Flashpoint.
Her powers hadn't manifested themselves yet, so there was no way for science to have detected/predicted that she was going to manifest them.
Caitlin would've gotten powers regardless; they just took a while to show themselves.