early signs of pregnancy?

I'm trying to figure out if my symptoms are any pregnancy symptoms or just period? Also when is it the best time to test? My first day of my last period was May 18-20 area)
• bloated/fatigue(constipated feeling sometimes)
• slight cramping
• cravings/always hungry feeling
• increased in discharge
• back is killing me
• nauseous and some sickness
• dizziness/headache 
• feel like I have to use the bathroom more 
• tired more than normal
• nails seem thicker & shinnyer than before