period and pregnancy

period symptoms and pregnancy symptoms are literally equally the same and i think i missed my period by one day and i’m kinda freaking out but i don’t feel nauseous or anything like that i’m just constipated and have back pane but my last period was on Dec 1 and i should have got it today because today would be the first but it’s Dec 31 , i’ve had protected sex this whole month but sumtimes he goes unprotected but is very careful but its mostly protected this month so if anyone would like to help or explain that would be great