You have not mentioned why your daughter believes that she is pregnant.
Had she missed periods? Did she do any pregnancy test (urine or blood)?
You have not mentioned the name of anti-depressant medicine she is taking.
There are certain antipsychotic
medicines that can cause false pregnancy
test in urine (commonly done by preg-colour card). However, pregnancy test from blood do not show false positive in such cases. Please go for a blood test
for pregnancy to get the right report.
However, if she is pregnant, do not take the decision of continuing or discontinuing the medicine by your own. Vyvance - can cause damage to the fetus (Category-C by FDA) if taken in first trimester of pregnancy. But, if the patient discontinue the medicine, there may be severe psychotic problem.
Please get the confirmatory diagnosis of pregnancy and consult with your doctor regarding the continuation of medicine.