Your experience yesterday almost seems like the feeling you get right before you faint. Shaking, shallow breathing, everything looking hazy, the voices sounding distant. Maybe you were so nervous that you almost passed out.
It almost sounds to me like you might not be ready for marriage yet. That's find and completely normal. You're still young. Just because you've been dating for 2 years doesn't mean that you have to feel ready for marriage. That's a huge step. There's couples out there that have dated for several years before marriage. Don't worry about it too much.
I had a similar situation a few months ago. My boyfriend may have to move out of state for his doctorate (he's going for a PhD in Analytical Chemistry and the top schools are Chapel Hill, CalTech, Harvard, MIT, and Florida....guess which school I'm hoping he chooses?
). He wants me to go with him to wherever he goes to school. I told my mother this and she said, "Well, if you go with him, you better make sure that there's a ring on your finger." I suddenly got really shaky. Then, I began to hyperventilate. It was awful. I love him very much and we've been together for almost 3 years. But, that situation made me realize that I'm just not ready for marriage yet. Give me a few years. Luckily, he feels the same way.
So, if the cause of you feeling like that yesterday was just because you're unsure about marriage, maybe explain to your boyfriend that you love him and want to be with him forever but you're just not ready for that next step yet. He will hopefully understand.