[Lizzie]

First, ovulation calculators online are not reliable, as all women ovulate at different times and on different schedules. While there is a ‘norm’ for ovulation, it’s not a guarantee. There are over the counter tests you can take to see when you ovulate as well as talking to your doctor. That would be a much more reliable route.

Next, implantation bleeding occurs at least two weeks after sex, it cannot occur sooner than that because the egg does not implant sooner than that. It’s also a very small amount of blood that would not require a tampon. It’s more likely that your period was just a little irregular this month.

If you are still worried that you might be pregnant you can always take an over the counter pregnancy test which can be bought over the counter at most grocery stores or pharmacies. You have to wait until at least two weeks after having sex to be able to use it.