Hi there, I have understood your concern. I will suggest you the best possible treatment options.
1 ) First of all do not panic .
2 ) As there is history of unprotected sex act, and she has missed her periods, then please get morning's first sample of urine tested for
pregnancy.
If the pregnancy test results are negative, then you need not worry.
She can simply wait for the onset of periods or induce the periods with
progesterone tablets.
Your treating doctor can guide you further about the doses and withdrawal bleeding of the same.
Even if she is pregnant, you can can opt for termination of the pregnancy with medicines safely till 9 weeks of pregnancy under medical supervision.
3 ) As you might be aware that pre ejaculation secretions do contain sperms enough to cause pregnancy. and deposition of precum can take place without any symptoms.
I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar.