Need some advice from a good boxer/fighter please?

Ok, so, I know the technique for all punches, but my cross feels weird and weak, I don't know why. C|an you please explain how to properly throw one? Whenever i pivot my hips as I throw the cross, it feels slow, and that I'm telegraphing it, so what is wrong, and how can I fix it? Also, i have 5 lbs dumbbells at home, if that helps, but I dpon't have any bags, what can I do to speed up my punches? thanks