Relationship advice... Please read :(?

Okay so heres the thing... Ive been with my boyfriend for about 3 months now. He is absolutly amaaazing and treats me very well. Our personalities are very similar and never in my life have I ever been this close to someone. He absolutly adores me and tells me he wants to marry me. The problem is though, I am not that physically attracted to him. I went for him due to his decency and the fact that we get along so well. We havent had sex although we have done sexual things together. We are both virgins and he is my first boyfriend. We are both 19. I am so lost, I have no idea what to do. I dont think my feelings are strong for him :/