when is the earliest you can take a pregnancy test and get a reliable answer?

I am 4 days from my period and wanting desperately to know if I might be pregnant this time. I am having all the signs of my period but hoping and praying it is a baby this month. My last period began around Jan. 8th and I am usually 29 days or so.I think I ovulated late on day 17 (Jan. 24th)or so but not sure. My husband and I used no protection this month and had sex 4 times during the week I think Iovulated. I have been cramping for the last 2 days so I am a little nervous that it is just period cramping but looking for opinions. I know no on out there can tell me that I am pregnant. But am I crazy to think I could be?