When should i Test? Please suggest ladies !

According to glow my AF was due on 17 th Feb and last month i got AF on 21st Jan. I didnt get AF till now. I have cramps on and off, leg pain, little nausea at times without vomiting, back pain, dizziness at times. My CM has been watery and milky in medium quantity
Kindly suggest me when to test. 
Awaiting your valuable advice ladies !!