at different places

My boyfriend and I recently got back together after being broken up for a week (not over anything bad). after being together for a day or 2 he told me he loves me. and wants to be with me forever. I just don't feel like I'm in the same place as him. I don't know if I love him or if we can be together forever. (we're only 19 mind you). How do I know if I love him or not? I think I just might be losing feelings.