Please please please do not take yourself off antibiotics or change your own dose without consulting a doctor. This can cause you to become resistant to the antibiotic, and means that it will not be effective if you need to take it in future. This also allows bacteria to build resistance to an antibiotic and helps create and spread infections that cannot be treated with standard antibiotics.
I'm glad birth control is working for you, just please be responsible in how you are dealing with your medications.

my doctor told me to stop them whenever I want

Phew! Your 'wean myself off' line had me worried. Carry on!

 She actually said I can stop by either weaning or all at once and I think the first choice is better. I was taking 4 pills of 250mg a day and now I'm thinking of taking only 2 a day, but I only have enough pills to last maybe half a week.. Is that enough time?

I have never heard of anyone being told to 'wean' off antibiotics like that before, so I don't really think I can help you much. I would guess from the amount you have left that it wouldn't make toooo much of a difference either way though.
Maybe someone else on here has some 1st hand experience with this...?

I also think it's a little strange to wean off antibiotics...there should be a minimum dose that is supported by MIC data and if your doctor suggested you could cut back to 2 a day then well and good, otherwise perhaps you can call your doctor to confirm the lower dose. I don't see the timeframe of the lower dose being an issue at all.