7 cm Cyst

I am 2 weeks late and am for sure not pregnant. Had a transvaginal ultrasound and found out I have a 7 cm cyst on my right ovary. Haven't had any pain, only symptom seems to be missed period and possibly some slight dizziness. Have Dr appt with ob-gyn in 3 days. 
How worried should I be? Not sure what to expect.