There are quite a few examples of powerful women in Chinese History, though unfortunately a lot of the good they did was undermined by Confucian backlash. My area of expertise is the Three Kingdoms, which is a few hundred years after the Warring States.https://en.wikipedia.org/wiki/Wang_Yi_(Zhao_Ang%27s_wife
"When Ma Chao attacked Ji, Wang Yi donned a battledress, armed herself with a bow and arrows, and assisted Zhao Ang in defending the city from Ma's forces. She also handed out her personal accessories as rewards to the soldiers, substantially increasing the defenders' morale."
Eventually Ma Chao won and conquered Ji. She became chummy with Ma Chao's wife, which prevented him from harming Wang Yi or her husband. Later she plotted with her husband to take their lands back, successfully liberating it.
"For the whole period of time from the siege at Ji to the battle at Mount Qi, Zhao Ang had launched nine attacks on Ma Chao and Wang Yi participated in all of them"
Less dramatic, the poetess Cai Yan, kidnapped by barbarians, ransomed, and then recited 400 books, thought forever lost, from memory.https://en.wikipedia.org/wiki/Cai_Yan
You might consider playing a character who has a lot of relationships, familial in particular. Women of the period exerted a lot of influence by virtue of who they married or who they mothered. The Empress He was a commoner, but managed to become the Emperor's favorite. She rose her brother to the position of Prime Minister, but most narratives paint him as her lackey.
There is also Lady Wu, who was the mother of a man who declared himself an Emperor.https://en.wikipedia.org/wiki/Lady_Wu_(Sun_Jian%27s_wife
"Lady Wu was known for her wisdom and shrewdness in politics. The Kuaiji Dianlu (會稽典錄) recorded one incident in which Sun Ce wanted to kill Wei Teng (魏騰), an Officer of Merit (功曹) serving under him, when Wei opposed his views. The other officials were afraid and did not know what to do. Lady Wu showed up, stood beside a well, and told her son, "You've recently established a foothold in Jiangnan and there are many things you still need to do. You should treat men of talent with respect, pardon them for their minor mistakes and honour them for their contributions. Officer Wei has been performing his duties faithfully. If you kill him today, tomorrow others will rebel against you. I don't wish to see a tragedy occur, so I'll throw myself into this well." Sun Ce was shocked and he immediately released Wei Teng."
Not all of them were entirely benevolent, though. Nor were they docile and subservient housewives. https://en.wikipedia.org/wiki/Zhang_Chunhua
Once, the warlord Cao Cao wanted to recruit Sima Yi into the Han civil service, but Sima lied that he was ill and stayed at home. One day, while Sima Yi was drying his books under the sun, there was a sudden downpour, so Sima immediately rushed out to collect his books. The incident was witnessed by one of Sima Yi's maids. Zhang Chunhua was worried that the maid would leak out news that Sima Yi was well and get their family into trouble, so she killed the maid to silence her. She then personally prepared meals for the family, and Sima Yi was very impressed with her.
In his later years, Sima Yi favoured his concubine Lady Bai (柏夫人) and started neglecting Zhang Chunhua. Once, when Sima Yi was ill, Zhang Chunhua visited him, and he said to her, "Old creature, your looks are disgusting! Why do you even bother to visit me?" Zhang Chunhua was angry and she attempted to starve herself to death. Their sons did so too. Sima Yi was shocked and he immediately apologised to his wife and they reconciled. Sima Yi later secretly told someone, "It doesn't matter if that old creature died. I was actually worried about my boys!"