First of all, you should undergo one home pregnancy
test with urine to check pregnancy status as mid cycle unprotected sex with ejaculation is very much risky for being pregnant. Repeat test may be needed in this case.
If you took birth control pill regularly on scheduled time, then chance of pregnancy is less in case of one missed tablet. Though you need to confirm it. Following test report, you need to consult with doctor for next line management.
Take some analgesics, avoid stress/tension, take healthy diet with Vitamin & iron supplements
, control body wt and take proper sleep.