If she was already on her second pack of pills the two of you should be safe. It's the first month of being on them that you still need to use a back up method. The bleeding could be because of her pills. It's not that uncommon to have break through bleeding while on the pill, especially at first. Good for both of you for using birth control. I really do think you have nothing to worry about as far as pregnancy. If the bleeding and cramping keep up with your girlfriend though she should probably see her gynecologist. She may need to try another pill. Ovulation can be different for women. It really can be any time of the month. The only way she could know is to use an ovulation kit.
What about the missed pill? and the discharge?
it all depends on when she got her period. if u 2 had sex within 2 weeks after her last period, she mightve been ovulating and it can happen that ur sperm may have gone in. if she noticed she didnt get her period 2 weeks later and she started bleeding then it can be implatation bleeding or it may be a chemical miscarriage. it all just depends on how long after she had her period.
a week and a half before her up coming period which is this sunday!
If she does'nt start by Monday or Tuesday have her take an early pregnancy test. I really don't think she is pregnant though. It could be a possibility but highly unlikely. Please tell your girlfriend she has to take her pill every single day around the same time.