Ladies, need some opinions on commitment

Ok so here’s a little back story...my SO and I have been together for 5 years. Before we met he was married for 8 years but they were together for 15. I had a 1 year old daughter from a previous relationship when we got together. Once he divorced we started a relationship. Fast forward to today, he has legally adopted my (our) daughter (her biological father hasn’t been in the picture since she was 11 months old) and we have a soon to be 2 year old son together. We just moved into our newly built home a year ago and everything has fallen into place beautifully. The next step in my eyes would be marriage. We have had discussions about it and he has said that he does want to get married ‘some day’. I bring it up on occasion and I usually get the same response. How long should I wait? I feel as though I’ve given him 2 children and fulfilled his life on so many levels he should want to make me his wife. Am I delusional? I just don’t know how much longer I can wait. I don’t want to harass him or nag him into it but I feel like if I don’t talk about it than he will never do it. Thoughts? Suggestions? Sometimes I feel like he already has the kids and the house and the life so why bother marrying me...I just don’t know anymore...