Trying to Conceive vs Not Preventing

We have been not preventing for 2.5 years, but not actively trying. Most often, due to work and stuff, we have sex on the weekends (so about 2x/week but always on the same days as it happens) - only very occasionally doing it during the week. I track my periods but have never tracked my ovulation or anything. Do you think my not having gotten pregnant yet could simply be timing?