late period, light, on pill...

ok. so this may be kind of long. but here it goes. I'm 17, and my girlfriend is 18.She has been on birth control for 2 months. her first period on it was normal, the second one was late by 2-3 days. and it lasted 5 days. it was a lighter period than one of her normal ones, and her cramps were painful. she said she felt a little nausea one of the days, but she never puked. She was Very stressed for weeks prior, so im thinking thats what it is. She also told me she was on the pill a year ago and this never happened. Oh and the very important part of all this. she was at a party a month into her pills, and she forgot to take it. the next morning, at around 8, she took it. (she usually takes it at 10 pm) she doubled up that day and took the other one at the normal time. we had unprotected sex at around 9 PM, the next night (the day after the party) she didnt tell me she forgot until after i came inside her!!! >:( but its ok. her period lasted. she ran out of b.c. pills on the first day she was supposed to start her period (an orange pill rather than the normal white ones) but she didnt have sore breasts, she hasnt been moody, none of that...please help we are freaking out so bad this is terrible, we are remaining abstinent until we are ready! thank you so much