I'm right there with you, Nini. So long as you're feeling movement everyday (whether weak or strong doesn't matter) I wouldn't worry!
Babies vary all the way up to birth is what I have been told!! They, like us, have lazy days and active days. Like chantal said you should feel so many movements in so much time. Sometimes if you are walking alot (or just moving around alot for that matter!!) you can "rock" the baby to sleep or just not feel him/her move!! If you get really worried you can try drinking something like OJ and eating and then laying on your left side....that is supposed to make them move!! Although mine always moves when I lay on my back for a little bit!!!
My baby is never completely consistent with movements and I am 29 weeks. At night the baby seems more active though and the kicks are much stronger. But during the day it just depends. Some days baby is probably tired, and others more active. As long you are feeling movement that is the good thing. And you should feel about 10 movements, kicks, punches, anything, in an hour. But I think closer to 28 weeks the movements become more consistent and distinct.