I got a negative test tonight. should I trust it?

 I am on the pill (have been for over four months) and I use condoms when I have sex. None have ever broke. My boyfriend never ejaculates inside of me. Back in Feb on the 18th, my boyfriend stuck his penis in me without a condom once or twice. My period came on time a week and a few days later. I had sex prior to that period. Used condoms and none of them broke or leaked. I started my period March 28th and it ended on April 2nd. I had spotting for about three days after my period. It was pinkish red and sometimes brown. It was mixed with creamy white cervical mucus sometimes. It only happened once. I've been stressing out and freaking myself out so much. I noticed I have a line from mid pelvis down but it's not really dark at all. My nipples are purple, but I think they always are. I'm great about taking my pill. I always take it on time. I took a pregnancy test the day before I started my period and and 4 days after my period ended. Both were clearly negatives. 
 I've had sex since completely freaking out and the condoms were great. No holes or anything. Am I just being crazy and bringing these symptoms on myself by stressing out so much? Or could I still be pregnant? Any explanation would help tremendously. I've very scared and anxious. I'm only 18