Boyfriend and I together 5 years- will he ever marry me?

My boyfriend and I have been together for 5 years- lived together for 4. Im 26 and he is 31. He says he will marry me and he definetly wants children but he doesnt bring it up a lot. He says Im the best thing that ever happened to him and he wants to be with me forever. I am one of the few remaining unmarried girls in my circle. Both families are putting alot of pressure on us - Im now stressing that he will never marry me (due to other women saying he wont) and in turn- Im stressing him out. I want to marry him as I love him -accepting both good and bad. Also, I feel like my biological clock is kicking me in the head because I was recently diagnoised with a medical condition that may make it difficult to have kids without surgerical intervention. He told his family (mom, sisters and dad) 2 months ago that he was going to marry me. He also told one of his best buddies a week later. Im just worried he wont marry me until we are old and it just becomes a means to an end- not a declaration of love. 2 weeks ago my baby cousin got married and now the pressure is really on. What should I do and should I just give up on wanting to get married because I want to be with him? How do I keep myself from pestering him about it?