I have been urinating a lot lately and I've had tender and sore breasts and I've been a week late on my period now and I've had pains in my lower abdomen. But those are the only problems I've had so far so I don't think I'm pregnant.

I wouldn't put money on it either. It could be a bladder infection, or PMS, or just stress induced hormonal imbalance. The most reliable symptom of early pregnancy is a missed period, all other symptoms can be explain by other things. I would wait for another week to see if your period comes, if it doesn't then take a pregnancy test using your first urination of the day. If that comes up negative and you're still experiencing these symptoms, I would make an appointment with your doctor.