She didn't fumble her career per se, however I do think she missed a big time opportunity.
She was always going to go down the actress path, and when disbandment came, she seemed like she was done with the idol life, and wanted to pursue her other passion straight away.
However, if she was to invest another 2-3 years into being an idol, I think her celebrity status would've elevated a lot more, and would lead to bigger opportunities for her as an actress. She could be getting lead roles straight away, rather than having to grind for 5+ years before landing a main role like how other actresses normally do.