He is a bit daft if he doesn't want more kids yet forgets to use a condom but contraception is a joint responsibility so you should remind him. I think it would be morally wrong not to and what if he was really unhappy if you did get PG? As much as it would be equally his fault, it still wouldn't be a great situation
Tell him (outside of the bedroom) that you would like to get preg again, you are not willing to use hormonal BC, and so if he is up for another dc you are happy to not use condoms, but if he is not up for it he needs to be responsible for buying and using condoms every time you have sex.
Sorry, it's not morally wrong not to remind him to put a condom on unless he's so stupid he doesn't realise that unprotected sex can lead to pregnancy!
tell him up front when he's not horny 'just so you know love, i don't like using condoms and want another baby so i won't be buying them any more or reminding you to use them. if you choose to buy them yourself and use them so be it but i won't do it for you'
that's how i got ds, after ds he actually managed to buy and use them for almost 2 year and then miraculously decided not to.. am now 18 weeks