Ambivalence about having kids?

I've been with my boyfriend for about 2 years and last week we started talking about getting engaged. He suggested getting some pre-marital counseling which I think if a good idea. One issue that I've been grappling with is deciding whether or not I want kids. My feelings have been mixed; on one level I think I'd have a lot to offer as a mother but on the other hand, I'm scared. Also, my own mother has been trying to talk me out of having kids for years even when I expressed an interest. The truth is is that I've been reading a lot of negative stories from mothers complaining about how much it sucks, but I know that's only one side of it. I also read an article about a mother with an autistic child which created a frightening picture (I was thinking "what if that happens to me?") I told my boyfriend that I didn't really want kids but now I'm starting to rethink it (which I mentioned to him btw). After traveling with him to meet his family and seeing how he is with his nieces, I don't want to close myself off from that possibility. My thought was that if I did have kids, I would only do so under the right cirstances. My boyfriend is the most considerate, kind, loving and affectionate man and I feel privledged to have him in my life. Plus, I think he'd be extremely supportive, too. I didn't have the best childhood myself which can also be a reason not to, but at the same time I think it's made me more sensitive and aware, too. Is it normal to have these feelings?