Congratulations! You have been granted a miracle. And for the rest of your life you will be able to smile and tell people that God is the author of life and it is not in our hands. He gives children to people who did not expect them. There is biblical precedent for that, you know.
The Blessed Virgin kind of found herself in the same boat. (Though without the sin part). Ask especially for her help, intercession and guidance during this time. At least your family and village elders aren’t going to take you out into the public square and stone you. What’s the worst that could happen? Your mom cries a little and your father sits there and thinks “There but for the grace of God go I…” (No, I’m not judging him. I’m just looking at the law of averages of men of that generation…)
Fact is, as another poster said, you’re probably not the only one among us who has sinned. (Insert chuckle here.) You’re just the one that God drew a circle around.
Think of the joy it will bring her family. And yours. They won’t disinherit you. They want to see their grandbaby. And think of the people who will take courage from your fiancee (that is what she is, right?) and believe they may beat the medical odds also.
This is an opportunity for you to show grace and humility. Not fear and irresponsibility. Forget what everyone else thinks. Everyone has their own sin issues. The product of yours will just be much cuter than most people’s.
As for the wedding… Holy Mother Church, in Her wisdom, doesn’t really do shotgun weddings. You may be able to get a dispensation. Some dioceses make this on a case by case basis.
I think the question you need to really pray over, and this is the determinative question: if, God forbid, she miscarry in the next few weeks, would you still go ahead with a wedding? Would you still hurry the date up? Your answer to that question down in the deepest part of your heart and soul should be your guide as to what to do next.
You have a lot on your plate for the next year. Getting married is a huge adjustment. Then God gives people nine months to get used to the idea of parenthood. (Some people never get used to that idea, unfortunately.) You are compressing both major events into the next 8 or so months? Proceed very carefully. Make sure you are on solid mental, spiritual and emotional footing every step of the way, no matter which path you choose.
And make sure you increase your Mass attendance and visits to the Blessed Sacrament. There you will find your answers.
This is between you, your fiancee, God and this new life. Everyone else is really immaterial right now. And those who say the most now may be the ones to have to eat the biggest words later.
God bless you and good luck!
(and remember how many tragic people are out there who abort to keep a public image, but live with self-loathing and sadness the rest of their lives. There is really no such thing as a hidden sin. Now make your redemption and strengthened relationship with God just as public for others to follow your example.)