Pregnant?

I'm a week late on my period. And I'm never late ! The only time I've ever been late is a few months ago but I was only 3 days late & on the third day I got my period. I was extremely stressed so that explains it. But I haven't been stressed, nothing's changed in my life & I'm a week late. I'm super tired lately, my breasts are sore, and I've been getting bad headaches. Should I go buy a pregnacy test?