We are cousins (on the maternal/paternal-aunt side) and grew up together.
Tips
culture
The 表/堂 split is fundamental to Chinese kinship. 堂 (táng) = same surname (father's brothers' children); 表 (biǎo) = different surname (mother's siblings or father's sisters' children). 表姐妹 = the female 表 cousins; older are 表姐, younger are 表妹.