That's it, really. (and I ought to know about this, but I lent my LLL 'Breastfeeding Book of Answers' to a friend when she had bf probs and haven't had it back yet!) DS2 is 14 m and breastfeeding happily - maybe 5-6 times in 24 hours? My periods show absolutely no sign whatever of returning. Cervical mucus occasionally looks like I might have ovulated but nothing happens approx. 2 wks afterwards. I did once get some reddish smears, but nothing else happened. And sometimes I get the odd twinge. 
DS1 was breastfed for 26 months (and then I stopped mostly because I was about 6 weeks pregnant and fancied a break for a few months!). I think my periods came back at about 7 months with him, yet I'd swear he was requesting his milk a lot more frequently than DS2. The only thing that might be significant is that I'm cosleeping with DS2 and didn't with DS1. But DS2 only tends to have a feed at 11pm and another one before about 7, when he wakes (and feeds) - he very rarely feeds more than that at night. I know that every mother:baby pairing is different, but should I be concerned at all? We don't really want to have another baby but I'd like to know that everything's ok down there.