Of course you could still be pregnant, anything is possible. I agree that maybe at this point a blood test at your dr. is the best bet so you can put the doubt to rest. Those tests are really accurate but I suppose you never know... It's also true that if you are waiting and stressing about your period, whether you want it or not, it can definitely make it late and mess up your cycle a little. This has happened to me before in times of stress and mental preoccupation!! Don't be too upset if you are not pregnant - you have so much time and you surely will be soon if not right now. Enjoy having your son as an "only" while you still can! Having kids is such a wonderful blessing but it is quite different going from one to two... you will get there, so just enjoy the moments of trying now!