If your period is due, then you should be able to test and get an accurate answer unless you ovulated late. If you're expecting your period today, having sex twice this week doesn't make much difference since you've already ovulated. Give it another few days and test.
You can test as soon as your period is late... if its still negative and you havent gotten your period in a few days then take another test... use the first pee in the AM as its most ocncentrated....