How old was Ying Si, the king of Qin, when he met Chi Yue?

In history, Qin Huiwen Wang 19 years old ascended the throne and killed Shang Yang. In the TV series, Ba Xing Mi Yue was born this year. This is 338 BC. Suppose Mi Yue was 16 years old when he met Shang, then Shang was 35 years old.

It should be noted that this may not be in line with history. Because our eldest sons, Qin and Ji Wang, were born in 325 BC. Mi Yue should be more than thirteen or fourteen years old at this time. Therefore, her birth should be earlier than 338 BC. The age difference between her monks is not as big as 19.