I stopped taking my birth control because of break through bleeding and now im on it again. could this make it less effective?

Take pill regularly: So long as you take your pill everday at the same time, it will be 99% effective regardless of what happened in previous months. If you are late or miss a pill take it as soon as you remember even if it means doubling up for a day or two to stay on schedule. But use a back up method of birth control if you take a pill 6+ hours late.