Medicines alone for ending a pregnancy generally work only in the first 9 to 10 weeks from your last period, not from the date of intercourse itself. Waiting till mid December would very likely put you well past that window, so medicines may no longer be an option by then.
Next Steps
If your period is late, take a home
pregnancy test as soon as possible rather than waiting. If it comes positive, see a gynaecologist within this week, since timing matters far more here than how busy work is.
Health Tips
Please don't try to self-manage this with medicines bought on your own. The right option depends on how many weeks along you are, which only an in-person check can confirm.