Improving my baseball swing?

I'm 15 and my swing has left my hands blistered, calloused and hurting over the last couple years. The blisters/callouses are at the top of my palm at the base of each finger. I grip my bat on my knuckles so I can get a quicker swing. Recently, a couple of my callouses have blistered and torn off and now there are just small callouses and my hands hurt when I swing. Is there any way I should hold the bat differently? (I currently own the Mizuno Pro G3 batting gloves with little padding. Should I just get new gloves?) Also any batting drills are extremely welcomed.