Hi,
It looks like you are looking for someone to tell you what you want to hear. I will tell this to you. Do I agree with it? That dosen't matter.
Yes, you should marry him. Obviously you two are in love since you've been together for a long time. You are not in the relationship for money so it dosen't matter if you sign the pre nup or not. Go sign it, get married, and live happily/unhappily ever after.