Missing cat, Melbourne

Domestic Short hair as thick as Russian blue , female 5 years old , BUT her colour is Tortoiseshell and white, she has four white feet socks and a creamy end of tail like a ringtail possum. She has black freckles on her nose and is quite small in size. Was not wearing her collar but is microchipped She has been an indoor cat all her life … only venturing as far as the doorway at from of my house on Raglan street and the back alley door of my back yard that opens into Cecil place…. She was with me on the early morning of December 27 and after watering my back yard around 7.30 am I realised she was not about and went to look in my house … searched and searched … and I’ve have not seen her since. I can only think she may have jumped from a chair onto the fence and got out but I am mystified as to why . She is very shy and timid and will not know her back alley hood… It’s so out of character for her to just go . The back door was closed and I cannot recall ever opening it that morning providing her with an access into alley way and then Cecil Place and other streets. She will be silent and hiding near by I hope and will reach her threshold for need to find water soon …. I have been outside with a torch at midnight and at 4.30 am … when ambient sound is the most quiet . I have out water bowls out …. So many people are away so traffic is minimal ….