Not following this at all?
What is 'ovulation bleeding?' And if you expect to ovulate in 4 days, how would you think you are ovulating NOW?
Women spot. It happens. It can happen for lots of reasons -- or no reason.
You don't say how you determine your expected ovulation date, but if you expect to ovulate in 4 days, (and your estimate is accurate) and had sex yesterday, that would put you on the outside edge of your likely fertile range. Pregnancy would be *possible* -- but not very probable. (Yes, sperm CAN live for 5 days. But the number of healthy, viable sperm still present in your tubes at that point would be low. Better to try 1-3 days before expected ovulation.)
Forget about the bleeding. It means nothing. If you have very regular cycles and know you usually ovulate around day 16 -- try to have sex closer to that day.