PMS vs Pregnancy?

So this is a question for those who have been/are pregnant and also always had bad PMS....
I always get sore breast, hungry, tired, bloated, headaches, mild cramps etc. before my period, so now that I am trying to conceive, I never know what to look for? I feel like it is a lot easier for some to tell if they don't normally have bad PMS. So my question is: was it any different when you were pregnant? what was different for you? Were you pregnant but had no idea because it felt the same as your normal PMS? Thanks in advanced!