Am I pregnant

I am a week late for my period today I have a few pregnancy symptoms like pain in my side nausea headache hot one minute cold the next although it is mostly hot flashes one minute I'm not particularly hungry the next minute I'm starving and eat everything in site etc took a test a 2 days ago and was negative why am I getting symptoms and am late for my period but getting a negative result does anyone know why this could be and let me if you have been through it so I know I'm not alone in this or going mad