Hi 紫瑤, I think you may be pregnant but it is too early to tell. How long is your normal cycle? You know you can do a home pregnancy test once your period is overdue. Sore breasts can be one of a symptoms of pregnancy but many women experience sore breasts before their period. I'd suggest you wait for another week or so then do a pregnancy test if your period still hasn't started. Meanwhile, you should take care of yourself as you are pregnant. If you really worry about it, you can go to visit a doctor and see if they can do a blood test to find out whether you are pregnant or not.
I wish I could feel the symptoms like you do now. I am also waiting to find out if I am pregnant but I guess I am not that lucky... keep my fingers crossed.