Early symptoms?

So I’ve had two babies already in the space of two years. Suddenly I’ve had nausea the past few days. My last period was 18th June - 21st. We also have used protection but my question is would pregnancy even be a possibility since my last cycle ? I highly doubt I am but I have the same nausea and being put off food , heart palpitations which I saw some people had as a symptom With both my my other babies nausea & being put off certain food was one of the first signs for me. Just wondered if it’s a possibility? It says my period is due in like 6 days. I’ve ordered a early test to come tomorrow which you can do 6 days before a missed period. What does everyone else think? And what was everyone else’s symptoms before a missed period