Hi I'm knitting a sweater that has a heart pattern across the bottom. but when I'm doing it I see that the holes that are supposed to be there are not there.. I'm thinking that my knitting is to loose and maybe I should try using a smaller needle so it will make it tighter...Please help

Is it a pattern that has you doing yarn overs? I imagine this is what you mean by holes that are meant to be there. If you make a yarn over and on the return row purl into the back of the yarn over, it will close up the hole. Perhaps this is what's happening?