Yes, if you have a normal cycle (which is, on average, twenty-eight days, though it varies from woman to woman), then your period should have arrived around February 20th.
However, something to keep in mind is that, although they're helpful for having a general idea of when your period is due and when you're fertile, pregnancy, ovulation and period trackers can't accurately tell you when you've ovulated or when you're fertile based merely on dates. That's because sometimes we ovulate earlier than expected, later than expected, or, sometimes, just not at all. An app won't know that unless you're also temping and charting.
You should take one more test. If you ovulated late, it's possible that it was too early for a test to show positive. If that test is still negative, then you can call your doctor or OBGYN and let them know what's going on. They can perform a simple blood test that's usually more accurate and sensitive than a urine test to check for pregnancy.
Unfortunately, it's that time of year when we're all passing viruses along to each other, and it's possible that your off-feeling and late period have to do with a virus.