Missed period, need help please?

So I am 14 years old and i haven't had my period this month, I have had my period for just over 1 year. I am a virgin (duh) & have been given Tetralysal Capsules prescribed by my doctor. Could it be the pills or have I got my menopause early (my sister was diagnosed with 'long menopausal' or something (not sure) please help?