My blokes quite a bit older than me and has two grown up(ish) kids. He said he didn't want more kids (long story, his ex tricked him into the first one, turned into the psycho b*tch from hell, used kids against him etc etc). When I first met him I wasnt that bothered but in the past few years i've been feeling diffirent and now I'm the broodiest person I ever met! I approached it with him a few times and he was a bit like, "oh well maybe". I decided that if I didnt have kids I would live to always regret it and would end up resenting him and obvoiusly it's not an option to trick someone into having kids (imo even if he accepted it and got used to the idea he would always feel resentful that his choice was taken away). I told him we needed to talk about it seriously but didn't tell him that if he truly ddnt want to have kid then I would leave him (I absolutly love him but theres no point if you cant both be happy). I didn't want it to be an ultimatum. In the end he just had a few understandable worries and I set them straight and I'm allowed to have babies! (fingers crossed).
Anyway what my point was was maybe you could try talking to him and say that you really need to know if he wants to have kids or not, not a vauge answer. Tell him its really important for you to know, he can't expect you to wait for an answer for ever. See if he has worries and see of you can work through them together. If he really does not want them then you have to decide what you want to do. It's not something you can compromise on and someone will always feel resentful if made to do something they don't really want. Good luck xx