This info from Wikipedia may help to clarify the 17/19 seasons issue:
Since its debut, American Dad! has broadcast 344 episodes (as of December 19, 2022). The total number of seasons and organization of episodes within those seasons are in dispute due to discrepancies in how official sources report this information. One model suggests the first season of American Dad! comprises the first 7 episodes, while another model suggests the first season comprises 23 episodes.[9]
Beginning on October 20, 2014, TBS picked up the series for the 12th season following the final 3 episodes airing on Fox as the 11th season. TBS and Cartoon Network (via their late-night block, Adult Swim, both owned by Warner Bros. Discovery), air reruns of the series.
On January 15, 2020, TBS renewed the series for both 18th and 19th seasons.[10] The 19th season premiered on January 24, 2022.[11] On December 16, 2021, the series was renewed for seasons 20 and 21. The 20th season is scheduled to premiere in 2023.