Welcome to HCM.
You are taking VYVANSE
50 mg. It is given in ADHD
for modifying psychological behavior.It has several side effects but effect on menstrual cycle is negligible or may be irregular in some cases.
You have missed period of more than 7 days and urine for pregnancy
test is negative.
It is seen that period becomes delayed or irregular with psychological problem,emotional upset or with weight loss
So,it is better to wait another 7 days and if your period not come,repeat the urine for hcg test.
If test is negative again,then need some intervention to check underlying pathology like USG lower abdomen, LH/FSH,Thyroid profile etc.
Another thing,if you are planning for pregnancy,then try to avoid taking VYVANSE with consult of your doctor as it is harmful to fetus.
So check your result and consult again with your physician.
All the best and take care.