Lol I think am crazy

I been having heartburn it started like 3 days ago and I am also 4 days late for Af Am Scared to test I think I might test on Sunday Morning Just to Be 7 days late could I be pregnant or is itt mind playing tricks on me I been ttc for about 18 months am nervous and excited at the same time cuz ive never experienced heart burn what do you guys think ? Btw I took a test dec 1 and it was negative pleasee help TIA !