Possibly Pregnant?

On Friday the 6th I will be four weeks late on my period. At around 2 weeks I took a pregnancy test that came out negative. Currently I have a headache nearly every day, I can't lay on my stomach without getting nauseous, back/side/hip pain, I can't wear a shirt without a bra as it irritates my nipples, and very moderate heart burn. We typically use a condom but have simply pulled out many times.  Should I test again?