I was one of those types to be afraid of getting married....and I'm a woman....I always thought that romance without marriage is far better....and felt like marriage is end of the romance....not sure why I thought that way, but it was kinda true in my marriage time....It didn't last even two years!
Now that I'm older, I feel the need of having a partner with me.....and having kids....still not sure if marriage is the key of success in a relationship....if you love your partner, you will love him/her forever no matter if you sign a piece of paper or not!!!
About him visiting his mother.....please don't compete with his mother and don't make him to choose between you guys....that's really sad....She is his mother and she will be his mother for rest of his life....be nice to her....even I heard that guys who respects their mothers are good guys in relationship....so cherish this behavior in him....
But I can hear you being worry about having kids....just let you know, you still have lots of time....even I read an article saying how women are postponing aging by getting pregnant in their 30s now....It was an study about it....very interesting.....It was saying genetically, women will age later if they get pregnant later in their life and they will give that gen to the new generation....crazy...ha! True or not, but it gives me a bit of hope
take care
Marjan