Are you on a combined oral contraceptive? And, what does your pill packet say about missing a pill? Most pill literature (the packet that comes with your pills) says that missing only one pill should NOT compromise your protection, as long as you later remembered to take it.
The fact that your pill schedule has been rather erratic is probably the reason for your bleeding. In my opinion, you did NOT compromise your protection by missing one pill since you remembered to take it. Even in both instances, you should have still been protected (as long, however, as you are taking a COMBINED oral contraceptive pill).
Remember, actually becoming pregnant is a very complicated process, and your pill does everything in its power to prevent that. I know it's easy to get paranoid over these things, and I hope everything works out for you!