Hi tiff,
i would not worry to much.

Firstly my doctor told me it not a really big concern to take anti-biotics with the pill, the reason they say it can is because when taking anti-biotics it can upset the natural balance in your stomach may affect you digestion/absorbtion of the pill. (at least this is what my doc says)

secondly they usually say use protection for 7 days after you've finished your medication (just to be safe) since you say it was three weeks i'd say you're pretty much fine.

Dont worry to much, stressing out can make your period delayed.
Let us know how it all works out.

Steph.

Hey steph:

thank you so much. Your insight has been very helpful in easing my mind a bit. I know that many drs have very different points of view on this topic so it's nice to know your Dr. Has given the same advice on the combo of antiob. & b.C. As my Dr. I think i'm fine.

Thanks again & have a good day!
Tiff

If its the pill free week, you have nothing to worry about. Most women can't get pregnant at all during this time period.