Been off bcps for 4 months and having very light, regularly timed periods. but ovulation tests r all neg. what could be wrong? can i conceive?

Oligo-ovulation: The most common reason for period problems after using birth control pills is a 'lazy pituitary', where the pituitary hormones that stimulate follicle development in the ovary are low. Time usually repairs this, but it is worth talking with a fertility specialist if this problem persists more than 3-4 months. Fertility is unpredictable, but often low, until ovulation resumes.