A: First:
Seek Allah's forgiveness for what you have done and the delay of the expiation for what you committed,
May Allah forgive you. You have to make up for that day.
Second:
The expiation for sexual intercourse during the day in Ramadan is: Freeing a slave. If impossible, a person may fast for two consecutive months (sixty days). If they can not fast, they may feed sixty needy people half a Sa` (1 Sa`=3 kg. Approx.) for each needy person, and the half of the Sa` is almost 1.5 kg of barley, rice, or the like of the staple food of your country. If the reality is as you have mentioned that you can not observe fasting, you may feed sixty needy people and nothing is sufficient except that. You have to inquire from those who know the needy people to give them the expiation. May Allah facilitate your affairs and forgive you as well as all Muslims. If you gather the needy people for lunch or dinner, it will be sufficient for you.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.