First of all there are plenty of people with similar issues as you guys have, we all have problems, that is for sure.

If he wants to grow up then part of that is learning to be a man and communicate with you, and listen to you.  So tell him how you feel, and if he is truely growing up then he will most likely be able to have a great conversation with you.

Maybe you ARE being a little too worried, but that anxiety stems from somewhere and he needs to realize that and mend it.  But remember even some of the oldest and wisest people who have ever lived including Jesus have had child like minds, in other words that imagination that love, holding on to things, and open-mindedness.  Sure it is good for all boys to become MEN, but it is good to be like a child as well.

Considering he says that he loves you and is willing to work it out, that means a lot.  But make sure that that is the sort of love that is willing to not only work it out but to do anything for you even if it means being your everything.  But that doesnt mean he doesnt want to be, im sure he does.

Keep praying! and have faith.  If you can make it this far, what's stopping you from making it further?  But you really need communication, honesty, purpose, more contact, and intimacy for sure!  And lastly although you are not a man and wont understand all that we think, that is simply an excuse, because you are a woman and we dont understand all that you go through either.  Saying that you just won't understand and ending an argument with that is what teenagers do.  But trust me this can work out, you just need to discover what the problem is, pin point it and conquer it, you will be so much stronger after you wont believe it.