am i pregnant

I had "sex" three times and all of those three times my boyfriend never ejaculated inside me only one time did we use a condom. i have had all of my periods regularly and on time and never missed one period. I have taken over 13 pregnancy tests and they all have came out negative. I just can't shake this feeling that i am pregnant i know logically i am not pregnant but i keep hearing stories of girls not knowing they are pregnant until 7 months and i'm so scared that will happen to me. i don't have anyone else to talk to about this so sorry. i don't really have any symptoms maybe nausea if i drink to much water and my boobs hurt before i get my period but that is only sometimes. i haven't gained weight i don't look pregnant. i guess i just want someone to tell me i'm not. idk.