Pregnant??

I was wondering what is the earlist some of you realized that you were pregnant? I am a mom of 3 so of course I should know this BUT every pregnancy is different. Each time though one thing was the same and that was that I didnt know I was pregnant until after a missed period. The last few days I have felt "off". I have slight cramping were I would normally have period cramps, my breasts are tender and sore, I have had wild crazy dreams and thats if I can sleep and I am so tired and cranky. I have even started to break out on my face which is odd for me. I am not due to have my period for another week but I have heard of people say that they have some signs earlier than a missed period. I know I wont know for sure until I miss a period or take a test but it would be nice to know if maybe I am just crazy...??