There's nothing indicating for sure she was, even that Memory Alpha page just says she was a senior officer with Starfleet Command. I suppose the title "Fleet Admiral" kind of implies she was, isn't Fleet Admiral Akaar's title? But then, she only has the pips of a Vice Admiral, and head of Starfleet should be a full Admiral. This has me wondering, what about Leyton? One would think he'd be the head of Starfleet is he was trying to stage a coup, otherwise any officers who outrank him might have some serious objections to him taking control of the government. But then he too was only a Vice Admiral.