Could I Be Pregnant While Having A Missed Period, Negative Test, And Symptoms Like Dizziness, Nausea, Mood Swings, Heartburn, Abdominal And Back Pain?

Hi, I got married last month oct 7th and i missed my period this month when i did thr pregnancy test says negative and i am having symptoms like dizziness nausea mood swings heartburn and pain in back and abdomen. My cycle was irregular earlier but since last 4 months is regular how can i know whether i am pregnant or not?