Is there still hope?

I just used first response that says it can detect up to 6 days before a period is due. My period is in 4 days. Took the test and it's negative...do you think I could still be pregnant? I was so sure this month. I have been a moody bitch this last week. Arguing over anything and that was the same as when I was pregnant with my first.... This is so hard been trying since September and nothing is happening.