headaches, tired, moody, coincidence?

This is the first month we are not trying to not have a baby. In other words, not using protection. I am not expecting AF until feb 1 (my bday...) but I already feel a lot of pregnancy symptoms I had in my last pregnancy. Is it a coincidence? I don't know if it's even possible to have them this early, if it's all in my head, or being caused by something else. Might be stress since we are also in the house hunting process right now which is fun but emotionally exhausting! Our good friend announced her first pregnancy last night, I am so excited for them. It gets me thinking about us too though! 
Expected due date would be Oct 8 if I am pregnant.  Best of luck to everyone out there hoping for an October baby too!