TTC second baby and still BF first! Any advice?

Ma
Hi I had my first little boy on 6th Jan and now we've decided to try for our second. I'm still BF my 8 month old on demand at the moment though and my periods haven't returned as yet. Any other mums in this predicament? I know BF is a natural contraceptive but I don't want to stop until little man is at least a year. He has solids of course and loves his food but also loves his  milk too! My sister conceived her fourth whilst EBF and her periods hadn't returned either so it does happen of course but just wanted to know of any other experiences of those in the Jan group that are trying to conceive now too! Thanks xxx