Why won't he tell his mom about me?!

We've been together for a bit, well not aaalllll that long. Only about 9 months, but he keeps talking about wanting to spend the rest of his life with me. But he refuses to tell his mom about us dating. His mom thinks we are just friends.. It just makes me feel like I'm not good enough for him to want to tell.. I feel like it could be that he doesn't actually care that much about me, and is trying to get everything he can out of this relationship.. I may just be paranoid or something because of my past disappointments, but I don't know.. and to top it off he basically just moved in with me. I know what most of you are thinking "how old are y'all?!" blah blah blah that "I'm to young to be worrying about this." That "It's probably just puppy love", or "You're to young to really understand, this is all typical teenage love" blah blah blah. No, I get that I'm young and naïve I assure you that I know I still have a lot to learn and stuff it's just...I'm trying to keep myself from getting hurt again and not be overdramatic about things, and I realized that I'm rambling, but my point is who can actually explain or attempt to explain this to me like has anyone experienced this? what exactly did you do? I've pushed this aside for a while and even tried talking to him about it.. he just doesn't seem to want to even attempt to reason with me or try to ease my mind..so it's just been bothering me for so long..