Confused...

So I'm confused, can you only get pregnant in your fertile window or can you get pregnant at anytime. I'm suppose to get my period yesterday and it didn't come I've been bloating, slight cramps mostly on left side but not like my normal period cramps, oh and only one boob is tender it's my left one only and it's not the whole boob is just behind the nipple, again not normal af symptoms for me. Oh and like slight neasua but not like where I'm gonna throw up just I guess queasy.. anyone ever had this..