Low progesterone?

Hi ladies! I am currently in my 3rd IUI round this month and just got off the phone with the office about my progesterone blood results. Has anyone had progesterone levels that have been drastically different from cycle to cycle? 1st month of IUI they were normal, 2nd month extremely low amd had to take prometrium in addition to crinone, and now 3rd month above normal numbers. None of this makes any sense to me! Anyone experience the same?