Very sore breasts. very short period three weeks ago. one positive then one negative test. possibility of pregnancy? next steps?

Test results: Best way to find out is to get a blood test for pregnancy.

MD evaluation: Although you have conflicting results on your pregnancy tests; there are other signs and symptoms that you are pregnant. See your physician who will order yet another pregnancy test, which if positive will arrange for a test that gives the level of a hormone secreted by the placenta and at some time arrange for an US.

See the doctor: It sounds like it's time for a serum pregnancy test, meaning a blood test. Call for an appointment with your primary care doctor. If you develop problems before the appointment like severe abdominal pain, bleeding and cramping, get checked right away.

Possibly pregnant: You need to definitively confirm pregnancy by a blood test which is much more sensitive than home urine tests. Your symptoms are highly suggestive of pregnancy. Avoid any smoking or alcohol until you are certain. You may need to stop any medications or supplements until you know.