I don't want to edit existing translations, but it's more accurate to say "We have to get married now, it seems. (Because I got pregnant)"
できちゃ is like a Shotgun Wedding.
I assume you're referencing 出来ちゃった結婚. That is at its most literal "done wedding", where the "done" is a euphemism for "gotten pregnant". So it's more that the Japanese term for shotgun wedding is "pregnancy wedding" rather than 出来る as a euphemism for impregnation automatically also implying a wedding. Here all she references is the pregnancy and nothing else.
