Break through bleeding can occur at anytime for any length of time no matter how long you have been on your brand. Break through bleeding can last seconds, minutes, hours, days, weeks, months. Break through bleeding can be any flow type from light spotting to heavy bleeding. As long as you have taken all of your pills on time within the allowed time frame and accounted for severe diarrhea or vomiting or any other interactions you are fine and protected. What you are experiencing is completely normal and you have nothing to worry about. Are you still in the 3-6 month adjustment period? If you are past the adjustment period then you could change brands to see if it would help. When you try a new brand your body will need to adjust again. There is another 3-6 month adjustment.