My period is supposed to start on sunday, I fully plan on taking a test if I miss it

But I've been feeling pretty off the past few days, especially today. I feel very light headed and a little nauseous. Last night I kept waking up with heartburn, which is super strange for me, the only time I've ever had heartburn is when I was pregnant

Did anyone else have this happen and end up pregnant? Curious if that's a common first symptom

Before my first symptom was sore breasts for both pregnancies