Even if she was experienced, I just doubt it since she's only fifteen years old. I'd feel that it makes more sense if she had the pills or a bullet. It just seems weird that a fifteen year old girl is in charge of the Yakuza...

EDIT: Read her history, but I don't think seven years is enough to master entering HDWM without pills or a bullet. Especially since her mother likely didn't know about it until much later. It took a year, near death experience, and even more training just for Tsuna to use his flames like that. Not to mention even if she was especially good at being a hitman, I just don't think that someone who was on the outside of mafia, brought in, then the head would know completely about flames and be able to train her daughter to that degree.