hello my cycles have been 28 days and like clockwork. This past month I used ovulation tests and thought I had a positive on 9th Jan although I had a test left and used it on 17th and it was definitely a strong positive. My last period was 29th December and I am now a day late. I have done a pregnancy test and it was negative. My Ovia app says to test in 3 days which would make me 4 days late. Is it normal to ovulate late and does this then make your period late?