Detectives issued the CCTV footage which shows Ms Davies walking with an unknown man on the night she was last seen and pleaded with a white van driver who could be a key witness.
Owami Davies has been missing for four weeks after leaving her family home in Grays, Essex on July 4.
CCTV images show her leaving a shop with another man just after midnight in Derby Road, West Croydon, on July 7.
Officers are keen to speak to the driver of a white van that was parked in Derby Road which Owami and the man crossed in front of.
The van driver would have had a good opportunity to see them both clearly and officers are appealing this possible witness to come forward.
Owami’s mother Nicol Davies said: “There are many friends and family who love and care for Owami and all of them want to see her safe return. Owami - if you see this appeal please believe you are not in any trouble, we just want you to come back to us.
“Please leave a message if you can to let us know you are okay, we are so very worried about you.“This is such a terrible time for all those who love Owami and I am pleading for anyone who can help find her to contact police. Every day we hope to hear the news that Owami is coming back to us, your help might make it so.”
DCI Nigel Penney, said: “We are working hard to find Owami but we really do need the public’s help. Owami is very vulnerable and the longer she is missing the more we worry that she has come to harm.
“As a result of extensive CCTV enquiries we have a clearer idea of Owami’s movements, but we still need the public to contact us and tell us what they know.
“Owami’s family are living through a nightmare and are desperate for news. I would ask anyone who thinks they can help to come forward - as the days pass the anxiety of Owami’s family will only get worse and your call could be the one they are praying for.”
Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter @MetCC. Please quote reference 22MIS025307.
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org