what do you think

Andrew and I are trying to conceive, I've felt kind of off latley. I feel so nauseous when I don't eat when I start to get hungry my nipples constantly hurt, and I keep cramping and I'm SO tired all the time. I'm "supposed" to start my period the 20th. What are your thoughts?. Another app I follow says to test in 7 days would this week be too soon?.