Sakura tended to do her best not to use jutsu she had to shout. If she did, they were usually diversions to distract people away from the actual threat. Or it was a genjutsu they already had no hope of escaping from. The point was: as a ninja she thought it was self-defeating to loudly inform her enemy of her movements.

The katon from the opposite side was something of a surprise, but just having been attacked from behind a moment ago, she reacted better to it, deploying a mud-net to deflect the flame from her directly. It didn't protect the tree, but if he was concerned about the trees he shouldn't be throwing around fire jutsu while amidst the trees.

She wasn't sure which of many techniques he was using to continue to attack from behind her, but she had no choice but to use the jutsu again. Air bullets, sooner or later she'd hit, and then she might be able to launch an offensive instead of defend again.