late n late again

last month I was a week late on my mense. I have a really regular mense normally. This month I'm late again. I'm a week late as of today. We've been trying for 5 months now and every month period time we both are hoping for a baby. Last month got us really good because I'm never late. but I even took a test last month n it was negative. we've been trying not to jump the gun cause it gets us both really down for a couple days after that negative. but advise ladies, should I just wait another week just in case it's late from stressing over this or I should just take a test?