Early Pregnancy symptoms

So I've been a dumbass and have been having unprotected sex the last 3 weeks so I know there's a possibility I'm pregnant but I kind of want to know if I should freak out a little now even though my period isn't due for 10 days and I'm usually late anyway. The one symptom that is bothering me is that my breasts that are normally floppy and not firm have been slowly getting more firm and bigger the last few(5ish) days and hurt like crazy and the actual nipple(not areola) is a slightly darker red than normal and they don't generally hurt much during ovulation or my period. I have been having god awful lower back cramps , stomach problems, some days I want to eat everything and others I just want to puke, and I keep peeing more than usual. But I'm at most 3 weeks, so all this shouldn't be showing up so early right? I'm probably just over exaggerating right?