How do you know that you are pregnant?

i just knew. its like my body felt different.my first pregnancy i thought i got cancer cz feel body different and period like chips more.had spotting on and off. then i check i was pregnant 6weeks. 6days after i found out i miscarried. my second pregnancy i felt different again. i just got feeling im pregnant. then i check im about 2-3weeks pregnant.now at 34weeks..