luteal phase

I have been googling what it means when you do not have a period three weeks after ovulation. It sounds it is pretty much impossible. The luteal phase should always be the same even if the cycle is irregular - it should be 10 -17 days. In the past it was always 16days for me.

Now it has been 23 days already but the urine test was negative every time. Maybe I should get a blood test..