Thank you for your reply :)
There were a couple of details I left out of my story, as I believe it's the dates which give conclusive evidence the child can't be mine?
She has told me that the child is mine secretly, although another guy is 'playing' dad...
We split up on January 1st, (two days after our last sexual activity) and that is the day she told me she was pregnant and had had it confirmed by doctors. At the time I found it all very suspicious, but I don't have conclusive DNA evidence and probably never will.
Sex on December 29 would produce a full-term baby on September 21 - 27 or so. If you had written in and said you were worried because she had her baby on September 28, you might have cause to wonder, but an October 29 baby would not have come from sex with you in December.
First off, if she were pregnant and had any doubt about who was the father (and thought you were one of the possibilities) she would have contacted you. She did not contact you. You ask whether you would be in range of being the possible father if she was "two weeks late" -- doctors don't let women go two weeks overdue. More to the point, if the last sex was in late December and the baby was born on October 29, the baby would be at least 5 weeks overdue, not two. Nobody goes 5 weeks overdue; doctors don't let them even get to 41 weeks. Don't let your overdrive mind convince you of something you have no evidence to believe -- she didn't contact you during her pregnancy, she wouldn't be allowed to go "two weeks" overdue, and she would have to be a medically impossible number of weeks overdue for the baby to come from sex with you. Relax.