If this helps at all I always change my cycles in the summer. I don't know why this occurs but it does. And adgal is very right, there are plenty of women having babies at 39 and up, so don't give up. Keep using your ovulation tracker this will definitely help you see your body's pattern.
That doesn't mean you won't have another baby at all. Sex 14 days after your last period is not necessarily the correct ovulation time, unless you have a 28 day cycle. If your cycle is shorter or longer then that, it is 14 days prior to starting your period (for most of us). You can try things like ovulation predictor kids to help pinpoint the correct time of ovulation as well.
I had my son, naturally conceived, at 40. I'm 42 now and still conceive rather easily (I have trouble carrying). If your period is still fairly regular, lots of women at 39 are getting pregnant and having babies. One irregular period isn't a big deal...happens to all of us from time to time.
just to let u know wasnt preg started period 4 days early n thats not like me.. take it am just not meant to hav another baby ...
Definitely keep us posted on this :)
Your chances are probably pretty slim. The good news is you will only have to wait another 14 days to find out for sure. Good luck and I hope the outcome is what you are hoping for.