Trying to get pregnant! Help

My boyfriend came in me September 12th, 13th, & 15th

Symtoms:

Bad headaches everyday

Appetite

Backache

Cramps

Constipation

Pelvic pain and cramps in uterus

Creamy discharge

Took a test the 20th it was Negative. ( added a pic of test)

When should i take another

test?