Could Lower Abdominal Pain With Cramping And Sore Breasts Be Due To Pregnancy?

Hi Doctor I got my period the 1st of December and around the 19th I had spotting for about 3 days; I haven't had my menstrual period since but I'm having sore breast and nipples and lower abd. pain with cramping. Can this be pregnancy signs? I took a pregnancy test 1 wk ago but the result was invalid. Thank you