I dont know whats going on..

So I'm kind of struggling here. Long story short, my bf came to visit (ldr) and we decided to just let nature take its course on when we get pregnant. Well I usually get my period between the 28th and the 3rd, and I missed last month and still haven't gotten it again. Ive had very light, brown spotting twice now that didn't last long. Ive taken a few pregnancy tests (pink dye, blue dye, cheapys and digital) and they all came back negative but I STILL havent gotten it. Im at the point where I may just go to the doctor but has anyone else dealt with this before? Im not sure what to think and its lowkey stressing me out