Hello dear
Understand your concern
If you are confirmed about your protective sex then no chance of
pregnancy.
As you have history of irregular period, it may be delayed so wait for period to come. If it will not come in next 10-12 days then go for early morning urinary pregnancy test AND OR BLOOD HCG TO CONFIRM THE PREGNANCY.
If your report for pregnancy will come positive and
you do not want pregnancy then you should terminate up to 9 week by using Abortion pill under the advice of gynaecologist.
If there is no pregnancy than cause of irregular period should be investigated like PCOS, hormonal dysfunction,
thyroid dysfunction by going for reproductive hormone analysis, thyroid hormone analysis.
In absence of pregnancy, period can be induced by the
medroxyprogesterone acetate injection ot by progesterone tablet.
Nausea may be due to Gastrointestinal disturbance and hormonal dysfunction.
Take small frequent meal and tablet
pantoprazole plus
domperidone or tablet phenargan
Avoid spicy and oily food.
Hope this may help you
Best regards
Dr. Sagar
Take unbutterd toast