Should I marry him?

My boyfriend and I have been talking about marriage. He treats me really well! I am comfortable around him. We have the same goals. We love being adventorus. He is a hard worker and well respected at work. He is handsome! There are two things that are holding me back from loving him completely. I feel shallow but I think about this all the time. I am not as physically attracted to him as I want to be because he is on the smaller side. Only a couple inches taller and he has a smaller penis than what I desire. I love feeling small and protected by a larger man. Is this something I should break up with him over? I fear if I break up with him I won't find someone who treats me as well. I also fear being with him and then being sexually frustrated and longing for other men. What do you all suggest I do?