It seems Prophet Muhammad definitely had eleven wives, and possibly more. These eleven women are: 1. Khadijah, 2. Sawda, 3. Aisha, 4. Hafsa, 5. Zaynab bint Khuzayma, 6. Umm Salama, 7. Zaynab bint Jahsh, 8. Juwayriyah, 9. Ramlah, 10. Safiyah, 11. Maymunah. These seem established, and this matches an Islam Q&A fatwa.
However, the Wikipedia page previously (18 January 2017) said: "...the thirteen women..." And the Islam-critical site WikiIslam writes: "...a total of fifteen women, though only ever eleven at one time.." (citing The History of al-Tabari (vol. IX) The Last Years of the Prophet: The Formation of the State.)
Question: Besides these eleven, who are the other possible wives of Muhammad?
Doing some searching, others possible wives include 12. Maria (listed here) and 13. Rayhaanah bint ‘Amr al-Nadariyyah (mentioned in the Islam Q&A fatwa), which I think is the same person as Rayhana bint Zayd on Wikipedia. There may be more I haven't found yet.