Thanks for the query to H.C.M. Forum. Dysfunctional uterine bleeding
, scanty menstruation
, irregular bleeding are characteristic features of poly cystic ovarian disorder
2nd reason in your case may be pregnancy so after 7 days of missing date , get in home pregnancy test for conformation of pregnancy.
Dizziness and vomiting may be due to pregnancy or tension & anxiety.
If no pregnancy then opt for ultrasound
of uterus and ovaries .
Consult a gynaecologist and get his opinion.