Hi M!
Though missing a period by just 2 days should not arouse such a great concern and worry, your day of unprotected sex is somewhere near the fertile period. You have got few options :
1. Wait for about a week. If you do not get menses, get
pregnancy test done on urine and/or by
sonography. If you are pregnant, you may go for Medical Termination of Pregnancy which can be done by few tablets. These tablets have to be prescribed by an Obstetrician. They have to be taken under obstetrician's supervision.
2. If you do beta pregnancy test, it is very specific and is usually conclusive 2-3 days after missed period.
3. You can straight a way approach an obstetrician and tell that you do not want this probable pregnancy. He/she can help you with medicines to terminate the pregnancy.
Please remember, it is safe to get the pregnancy terminated by medicines up to 9 weeks of pregnancy (5 weeks after the missed period). So please plan your actions accordingly.
I hope you have got your queries answered properly to your satisfaction. If any further explanation is required, You can ask me.