Late period

My period is always right on time each month, whether I'm stressed or not. This month, it is 5 days late. I know 5 days isn't too late, but it's kind of starting to make me anxious. Don't get me wrong, I want a big family... But my husband and I are both still in college. The past couple weeks I have have sore breasts and mild to moderate cramping with each cramp only lasting around 5 minutes. My husband and I aren't trying to conceive and are super cautious. I took a pregnancy test that came back negative, but I've heard of people getting false negatives. I know the only way to know 100% is a blood test, but I don't feel I need to go that route yet. Anyone have these symptoms the first few weeks of pregnancy? Or a false negative?