Trying to get pregnant again

I find it very frustrating that I don't know when I'm ovulating bc I haven't had a period since giving birth almost 10 weeks ago. We are trying to get pregnant again and just letting things happen but it's so hard when you haven't had a period and have no idea what your body is doing. I'm feeling nauseous but took a pregnancy test at 2pm (neg) so thinking maybe I should have took it with my first morning pee.