Ok this is my first month using the cheapy ovulation strips that literally have no brand name on them, all they say is LH ovulation strips written on them. Anyways I usually get a positive LH surge on CD 13-15 but this month I got a positive today which is CD 20!!! Is this typical to have such a shift or could it be these test strips. Uv never ovulated this late in my cycle. Has anyone ever had this happen??