Definitely take it slow to avoid problems for yourself and to make it as easy as possible on your boy.
I night weaned at 14 months to get my cycles back and it did not stop the night wakings. In fact, DS didn't start sleeping through consistently till he was well over 2. I would have just resumed night feeds but for the TTC thing - it definitely is easier. Anyway, it doesn't always 'work', depends on the kid.

Getting your partner to help during the night can work well. Sometimes cutting feeds shorter and shorter works. Or gradually pushing them back. You can also try explaining that your boobs are asleep during hte night, or that he can feed only when the sun comes up or something like that.

I think breastfeeding for comfort really is fine for toddlers, just like for babies. It's a really convenient way of offering comfort for mums too. Is it just the lack of sleep that's the problem for you?