Lateeee!

Jade
Hey guys! 
So I'm 4 days late and I'm very regular with my periods. My husband and I just got back from our honeymoon 2 weeks ago on Monday so y'all know lots of extra curricular activities went down while we were gone ;) 
Is it possible to only be a week along and the test not picking up? I took one on Monday but got a negative and if we conceived on the last day I would only be a week and a half along right now. Or am I just stressing over it too much? Oh and it doesn't help I'm a pee on the stick addict! I'm going to take another one this coming Monday to see what the results. Feedback? Suggestions?