If I feel tightness in my "uterus" area, does that mean I'm pg?

I have a 9 month old, and when I was pregnant with him I knew it because i had weird on again off again cramps. Right now, I think I may be pg because of the time my husband and I were intimate last... but I'm not getting those weird cramps, but I AM feeling that bloaty uterus thing you get RIGHT before you start your period, but I'm weeks away from my period. How early can you tell that you're pregnant? The cheap way, please, bloodwork and chem lab tests aren't an option! Ha ha ha.