Pregnancy related problem

Patient: Dear Doctor. I have gone through your site. First of all thanks for such a wonderful website to get assitence on medical problems.I would like to ask a question about pregnancy.My wife has following symtoms:1. Irregular period.2. Headache3. Feeling Vommiting4. Feeling like periods can start any minute5. Period date was expected on 29th Dec, 2011, but today is 7th Jan,2012, still there is no periods.6. During this period, we have tested the pregnance with pregnancy test, it was negative.I request kindly help me in this to make sure my wife is pregnant or not. Please help me in this.