With the past menstrual history and having missed your pills, pregnancy
should be suspected. This is because you were no longer protected in this cycle. Please go ahead with home pregnancy test with a fresh early morning sample of urine 3-7 days after the missed period. If positive, you can go for a trans-vaginal sonogram to see the status of the pregnancy. If you wish for an earlier and better confirmation/exclusion, please go for the estimation of the serum beta-hCG
titres. Hope this helps.