I'm a female sheep, and my boyfriend's a dragon. He's outspoken, and seems upset that I'm not.

My boyfriend is very outspoken in his love for me, and seems upset when I'm not quite as outspoken. He's going to propose soon, and I'm kinda scared about it. Not sure what I should do. We've only been together for a year, but I'm not yet ready for an engagement, and not sure how to be more outspoken about how I feel for him, when I'm not an outspoken person.