If you think you're pregnant, you need to think about if you've had unprotected sex, or if whatever method you/your partner used has failed. Birth control pills has a 2% chance of failing, meaning 2 out of 100 women get pregnant even when using them - condoms are about the same. Think about when the last time was you had your period. And then get a home pregnancy test, or go to a doctor, if you're still not sure.
Have you gotten your period yet?
Could be symptoms related to your period then. I know that's what happens to me.
My boobs get bigger with my period, or maybe just a little fuller. But if yours don't usually do that, then I don't know what else to tell you. Could be pregnancy, but depends on if it's too early to tell or not.