I really cannot wait to get married and spend my life with someone I love and I feel that I have found that person. We share a lot in common, have similar values and goals, and are both committed to learning and growing. The problem is that he is extremely immature. Sometimes I can see the man he can become and I think he just needs to break away that shell. But other times he sits on his free days in front of his TV watching cartoons doing nothing while he promised his family or me to take care of some things. How much should I help him? Is this a reason not to marry? Or will he eventually grow out of it and become a man who takes responsibility by himself and not only after being told several times?
You write that you and your boyfriend have similar values and goals and that you are both interested in learning and growing, and yet, from how you describe him, it doesn't sound that way. Someone who is truly committed to learning and growing doesn't spend their free time watching cartoons. I am wondering if perhaps your desire to marry which you begin with is not what is leading your desire to marry him.
You sound like a woman who appreciates and respects motivation and commitment. Yet your boyfriend does not sound the same. Perhaps right now you have a lot in common, but will he really continue to grow and develop at the same rate as you?
When you date and look to marry, you need to marry the person he is now, not the person he will become. For there are no guarantees that he will become who you think or hope he will become…especially if his getting there requires constant pushing from you. It is not your job to be the one constantly making him do what he needs to do. You should be his motivation and his inspiration, but it is up to him, not you.
If while you are dating--the time that he should be doing his utmost to impress you--he is not taking responsibility and not keeping his commitments to you, I would take this as a clear sign for how he will most likely be when you are married.
There is always the possibility that he will change. There is always the possibility that he will tap into his potential and bring it to fruition, but at this point he is not exhibiting those signs or giving indications that he will do that. It is not fair to him or to you for you to marry who he will become when you are not happy with who he is. I imagine you want him to love you and want to be with you for who you are now, not who he thinks you can be if and only if you change.
If he stays the same, remains as he is now, is this someone you want to marry? Is this someone you want to spend your life with? If the answer is "yes" then continue the relationship. If it is "no" then you cannot get married with conditions.
It is one thing to marry someone who is in medical school and feeling that you are marrying someone who will one day be a doctor and not perpetually a student. And something completely different to marry someone who is lazy, irresponsible and unmotivated, hoping that it will magically change in the future.
For now, be honest with yourself and be honest with him. But do not marry the person in potential unless you are willing and desiring to spend your life with the person he is now in case that potential does not manifest any time soon.
Much luck in your situation.