please no judging

So I have this friend who is on the birth control pill and is obviously very bad at taking it. She will miss two or three days and have sex during that time. She then will experience withdrawal bleeding and then go back to taking it again. What are her chances of getting pregnant? And can you still experience withdrawal bleeding and be pregnant? I have no idea how to help her as I'm TTC sp I no longer take the pill. Thanks for all the help please no bashing my friend.