I got mine back when DS was 8 months, had three cycles before falling prg again. And yes, they were regular 28 day cycles (which I hadn't had since my surgery pre IVF which was interesting...) but this differs from person to person and some women remain quite irregular while b'feeding.

And no, just because you're having a period, even a regular period, does not necessarily mean you're ovulating. My plan was to go and have some blood tests done to see if I was or not (for contraceptive purposes) but we didn't get that far - thankfully the universe had other plans for us!