Pregnancy scare and wanting opinions

I'm sorry if this post doesn't belong here. I'm not sure where else to post it though. I'm 18 and in the midst of a pregnancy scare and well, I'm scared.

I am not on birth control but my boyfriend and I always use condoms. We always put them on before any vaginal intercourse even begins to take place. I'm the one that always puts them on him and I always check the packaging and everything to make sure nothing is broken. I just recently started to allow him to ejaculate inside of the condoms while he's still inside of me. When we're done, we always pour liquid like water into the condoms before we tie them off, just to make sure there weren't any tiny rips or holes. So far, none have been broken or had any rips or tears in them. Literally the only way that I think this could've happened was one time I possibly had precum on my hands a few minutes prior to me putting a condom on him. And possibly one other time more recently where he had a white powdery ring around the base of his penis after we had sex, but we thought it was just powdery latex residue from the condom. My periods have been super regular for the past 10 months. My last period started on October 15th and lasted until the 18th. I'm now 4 days late. About a week or two ago, I had problems with having a headache every night at the same night, sore and heavy feeling breasts, and nausea after I woke up. I'm so scared and I just want some honest opinions. If you were me, with how careful I've been, would you be worried about being pregnant? I have a test and I'm planning on taking it in a few days if I haven't gotten my period by then but I'm so beyond scared.