I finally figured this out.
We are pregnant for 10 months medically speaking- because they count from the first day of your last menstrual cycle, but technically you are only fertilized for 9.5 of those months, starting at ovulation. Then- you only really "know" you are pregnant from week 4 (on average) onwards to 40 weeks, so 40-4 = 36 weeks/9 months of knowing/feeling that you are pregnant, when actually the whole "medical" cycle is a 40 week/10 month definition.
So at 36 weeks you are 9 months pregnant medically, but have only actually had a fertilized egg in you for 32 weeks/8 months. At full term you are 40 weeks, but have only been fertilized for 36 of them/9 months.
So at 33 weeks I have been technically pregnant physically for 31 weeks, and have "known" I am pregnant for 29 weeks, so I'll just say I'm 8 months pregnant because in 3 weeks I'll be 36 which will be 9 months!