How do you know there's a chance you could be pregnant if you haven't ovulated and haven't had a period? Basically, you mean you had unprotected sex before your first PP period? If that's it, wait a few more weeks, then test. And in the meantime, use a condom if you don't want to be pregnant.
You're 7 weeks PP - chances are pretty high that you aren't pregnant again. Not impossible, but pretty good.
It's okay to want to be pregnant right away again (I was/am in that boat), but if that's the case, then be intentional about it. Take OPKs to try to determine if you're ovulating soon.
ETA: I wanted to be pregnant soon after my son was born (with my doc's blessing). I didn't chart until I got my first PP period, then started charting again. You could start charting now, but it will just tell you after the fact that you ovulated, which is at least some information. Don't expect cycles post-baby to be the same as pre-baby. At least they haven't been for me and I'm 6.5 months PP.