well with my first pregnancy I knew with in days (or maybe hours). My breasts were so tender and I had to pee all of the time. My second pregnancy, I could have gone until I was 7 months and started to show before I knew I was pregnant. I had no symptoms at all! If I was heavier I could have been one of the people who didnt know they were pregnant until the baby was born. I really varies between people and, obviously, pregnancies. Good Luck and take a test to find out.
frequent urination (for me it was mostly in the middle of the night), SUPER tired, and maybe nausea. (although, I never felt any form of nausea that early)