Is reaching menopause in your 30's common in your family? If your family has a history of reaching menopause young it could be the beginning of it bit if not it is more likely that some sort of stress has delayed your period.
Hello,
If you are 19 days late, then a test would've picked it up so I don't think it's pregnancy. Have you been thru anything very stressful lately? I've been late before with no explanation, it can happen. You are a little young to be menopausal but that is also possible. It will be hard to tell for sure without going to the doctor. I know that isn't much help, sorry. Sometimes our bodies defy explanation.