She was 6 when she got married and 9 when the marriage was made official. She says that multiple times in many Hadith and Sirah books. This has raised criticism in the 20th century but before that, it was acceptable for girls to get married young as long as there physically and mentally mature for the marriage. The video explains it.Her age is unknown, and some claim she's 9 some say she's 19 so we cannot know 100%.