Missing Period Please Help Me!!!?

I'm ttc with my husband who is leaving for the army May 12th. We had around Feb. 23 and my last period was Feb. 5, 6, or 7th I'm not quite sure. I took a pregnancy test Friday but it was negative. I still have not had my period even though the website said that I should have had it three days ago. I don't have regular periods. Never have. I'm stressing out because we only have a short time to ttc, this month and next. We didn't know until about two weeks ago that he was for sure going to join. Do you guys think there is anyway I'm pregnant and should retest today or do you think it's just my period being all messed up. I'm going crazy because I'm worried that it's not going to come this month and I will loss one of the two months I have to try before he leaves. Help Please what would you guys do? I needed your advice!!!