what to do?

PLEASE READ

okay so I have been ttc for 3 months now. I usually start my period on the 17 and if not exactly the 17 it’s like one or two days late. I live with my mom and our periods usually start at the same time. Her period started two days ago and I still haven’t started but I’m still getting negative tests. Do you think I’m just more late than usual or should I get a blood test? Any comments are appreciated just please be nice :)

I usually cramp a day or two before my period but so far nothing.