Well, you're doing the only thing you really can do at this point - see your doctor. It sounds like you would need a blood test to determine if you're pregnant or not.
I do think that with nausea that strong, a HPT would be accurate - are you following the instructions carefully - using first mornings urine, etc?
Anyhow, the doctor will have a better idea on what to test you for. If your cycle has always been sketchy, then there could be something else going on - like an infection. UTI's can make you really sick as well.
