It's about a week before period is due and i'm tracking basal body temp, i have been getting really low temps of 68.7, do i have a luteal phase defect?

Pattern matters: When you look at BBT charts, what matters is the pattern, not the actual temperature. You should expect to see a rise in the temp about 2-3 dys after ovulation. Even though it may help you figure out cheaply when and of you ovulate, most fertility docs discourage its use since it not terribly accurate and doing it properly increases stress which makes it harder to get pregnant.