Why can't I shave my legs?

I'm 15 and I've always had a hard time shaving my legs. The only times my legs are as smooth as I want them are when I shave them after growing out the hair for some days. But it's not like I can wait to shave nowadays :p I use a Venus razor. I don't use shaving cream, I either use soap or conditioner. One day I can shave and they'll be acceptable to wear shorts. The next day they start to get prickly and if I shave my legs get irritated. I can't shave everyday! And if I don't my legs get prickly and weird :p And sometimes even if they are smooth, you can see like the roots but it still looks like hair! Like if the hair is under a thin layer of skin. I hate that I can't shave to wear my legs look hairless and smooth! What can I do so the roots don't show? And what can I do to prevent my legs from getting irritated when I shave everyday?