Symptoms or things to look out for before you know you're pregnant.

Kristyn • Trying for baby #2
What are some symptoms that are a sure sign that you could be pregnant? Today I've been having mild acid reflex... I've had cramping and floating. I'm not sure if these are just signs of AF coming soon. I am on CD 26, I am supposed to get AF on the 27th. Wanting to know also if this week is a good time to test? Or should I just wait for AF to arrive?? Help! :)