Can The Spotting After Taking Birth Control Pills Be Late Menstrual Bleeding?

Hello, I have a doubt concerning my girlfriend and I searched a lot on google yet my doubt persists. Here s the situation: My gf is using birth control pills, for more than 1 year, 3-4 days before the end of the birth controll pill s cartridge, she had a bleeding, the spotting, she had menstrual colics , the first day she had a brownish blood, and just a little, the next day a red blood but not so much, this continued for 4 days. When she finished her birth control cartridge, a bleeding is suposed to happen on the next 4-6 days, but she stopped tuesday 26/08 and until now she hasn t bleed yet! Here are some facts from us: 1) We ALWAYS use condons! no matter what 2) She started to have lactose intolerance so, these last days she had some gastrointestinal disorders 3) She s on university so from time to time she s under lots of pressure and some nights without proper sleep 4) It s normal for her to forgot the correct hour to take the pills, she must take them at 09 pm but usually takes it 10-11 pm, if she fall asleep she takes it 03-04 am My concerns and doubts: 1) Even if she take the pills 1-2 hours after the correct time, could this be the cause of her spotting? and the gastrointestinal disorder? 2)Can this spotting be the cause of her menstrual bleeding being late? 3)Can this spotting prevent her from menstrual bleeding this month? 4) If her spotting was just 3-4 days before the end of the cartridge, could this be her menstrual bleeding? Sorry my bad english and please help me! Thank you