Having Normal Cramping, Lower Back Pain, Sore Breast. Had Normal Periods. Whats Happening?

Hi, my girlfriend is 7-9 days late on her period. She is normally pretty regular, but she mentioned she thinks she s missed a period before we even started having sex. She is 24 and I m 25 years old. We have probably had sex 5 times this month. I use a condom ever single time and still pull out when I m about to go just incase. So ive never been inside her when ive ejaculated. Even afterwards I fill the condom up with water and there hasn t been any holes or anything. She s had normal cramping on and off, mild lower back pain and sore boobs which she normally gets. She s not moody and she said she feels fine. She is very stressed from work, barely eats, travels an hour to and from work plus 20 min to visit me, she has had a cold , barely pees (prob 3 times a day which is unbelievable), her stomach doesn t hurt, she doesn t feel naucious, she isn t moody, she has lost weight....I just don t see how she could be pregnant since I m very cautious, but I m scared cause we don t want a kid. We have been together for about 2 years and only been having sex for about 5 months. She was a virgin before me. I m just curious for a professional opinion as soon as possible.