My hearts not fluttering?

Is your heart suppose to flutter over a guy?
i dated this guy for 2 months now and he did make me flutter when he kissed me on our second date and I was nervous and all. He asked me to be his girlfriend last week and I did not know how to respond and I was nervous. I am quite timid and gets embarrassed in these type of situations. I want to say yes, but part of me says no. he's a great guy, but I like him and we talked all the time and get along pretty well.

I like the way he kiss which is a lot better than my ex, but how come my heart never really fluttered. Is your heart suppose to flutter over a guy?

I don't want to lose him and I know if we get together that out parents will get along and all. I want to meet his parents too because I have a feeling his parents will like me.

I just want to know why my heart isn't fluttering. When he told me he may not come back this week because his friends asked him to go clubbing. I got mad when he said he wanted go, but eventually he spent the day night with me. Why is my heart not fluttering, but get jealous?
I would also smile when I think of him but not flutter at all.
He surprised me with flowers and I think I fluttered a bit and I was ecstatic but not flutter like crazy.

I fluttered more with my ex because he gave me signs indicating he liked me and it made me curious and all, but is that why fluttered?

Can someone tell me what's wrong with me?

I think flutter is very important. If you don't feel the spark, maybe he's not the right guy for you. Probably good on paper, but chemistry wise.......something is missing.