If taking a birth control 8 hours later, could that really screw up two periods? making both of them lighter and bleeding during ovulation?

Some basics: Birth control pills work primarily by maintaining a level of hormone in your blood that prevents you from ovulating. Many will eventually reduce the amount & duration of menses. Ovulation bleeding is not expected since you should not be ovulating. Several hours delay in taking a daily pill would be unlikely to trigger much change. Skip a one or more & the hormone level drops & you may ovulate.