late!

I usually have my period on 33-34 days in my cycle but I am now 37 days in my cycle and no period!! 
Has anyone tested negative but a few days later tested positive? I'm only a few days late. Should I give it a few more days? Is there any hope? 
All I can tell is im really gassy! And I've been pooping a lot lol
Tell me how you found out? How late were you?