Help please

Hi everyone just wanting abit of help I'm not sure how long my cycles are but I had a period in August from the 26th for 5days I came off the 31st I had my period the 15th September which I came off the 20th on the 21st I had my cool out due to an infection although it was the copper coil no hormones I did have unprotected sex with my partner on the 26-29th as we already have a child n would have another if it happened I have not yet had my period but I have done pregnancy tests and only got a negative results help