I don't think the women who got pregnant without having a period just got pregnant without ovulating. What my doula told me is that they just happened to get pregnant the first time they ovulated after giving birth, and their body did not have a chance to menstruate.
There is a theory that when you breastfeed, your body will tell you when it is ready to be pregnant again (natural childspacing), which could be 6 weeks postpartum to years.
As you know, periods come back at different times - with my first child, it came back when she was 5 months old. My son is almost 13 months, and it has yet to appear. I got pregnant again when my daughter was 12 months. (you sure you want them so close together? - lol)
I breastfed her until 1 month before my son was born.
I think you might be able to get the mini pill from your doctor and it may tell your body to start ovulating. You would have to be on it for a few months (sounds like it's defeating the purpose, right?) and then go off and see what happens.
Good luck! I know the feeling of wanting to be pregnant again! Hope it works out for you!