I really didn't think I was pregnant, was so sure my period was coming due to what I thought was pmt but more extreme! My cycles are regular, 28-29 days, no idea when I ovulated but from around cycle day 18 I noticed the mood swings which were a lot worse than usual, I just figured I was having a bad month, my partner was terrified at my behaviour as he had not seen this before, the crying and irritability was particularly bad, just before my period was due it got even worse. Other symptoms I experienced from cycle day 18 was increased urination, dizziness, one small brown spot on cycle day 28 from an implantation bleed I guess and a mild flu like feeling that night I thought I was coming down with a cold, still felt a bit off next day and my period hadn't started so I decided to test and was shocked to see two lines, I was so sure my period was coming due to the mood swings I was so irritable! Came as a shock but my partner and I are so happy about it.