Had sex july 14, used condom, he did not ejaculate, started birth control july 13. what the chances i'm pregnant?

Probably not: If you are worried, you can do a first morning urine pregnancy test at home. You do want to use condoms as a back up contraception (and the best protection against STDs), at least through the first month of taking the pill, and after to be safest.

Very low: You tried to do everything right including the use of a condom, withdrawal prior to climax, and the start of an oral contraceptive. While there is a small chance of pregnancy if, for example, the condom was applied improperly or broke during intercourse, more than likely your are at very low risk for pregnancy.