Baby dates

Can anyone shed some light. According to midwife and scans i am 36 weeks pregnant exactly, but I've actually only been pregnant for 34 weeks because I know the date I conceived and they add the two extra weeks on due to menstrual cycle etc. Does this mean my baby is 36 weeks old or 34? I'm asking because I have a worry I'll go into labour early and there is quite a significant difference between a 34 week old and 36 week old. I have felt more relaxed reaching the 36 week mark but is my baby actually 34 weeks? Very confused.