The .444 Marlin is in no way "overkill" for Whitetail. The most common load for a .444 is a 240gr PISTOL bullet. I've seen a ton of deer (and I mean that as a literal of at LEAST a ton) shot by my Dad with a .444 Marlin. That old Marlin of his was one of his absolute favorite Whitetail rifles. He very rarely had to track anything he shot with it but when he did it was usually like tracking a waterfall. One of his favorite bullets for it was 240gr Rem corelokt. Another was I think a 265gr hornady interloc but don't quote me on the weight, it's been quite a few years.

As far as the OP's issue. It isn't the cartridge. The .308 has dropped almost as many big game animals as the 30-30. As has been mentioned, you need to switch bullets and definitely drop some weight. Since you mentioned hogs I am assuming you are down south somewhere. Southern deer are nowhere near northern deer size. That's BODY not rack. What you need is an easier expansion type bullet. The above mentioned 150gr Nosler is a fantastic choice and is usually quite accurate with the right powder. I have found the 150 Spitzer ballistic tip to be about perfect for the smaller southern deer. They expand a little too rapidly on the thicker hide and muscle on these Illinois brutes but they just create an internal mess on the lighter thinner southern brethren. Not at the house currently but I THINK I loaded mine up with IMR 4895 and was getting somewhere in the low 2800's if I am recalling correctly. I'm not a modern rifle hunter usually. I love my front loaders. But I usually do get out a couple times a year on out of state hunts to fill the freezers so I take a longer range weapon. We still have a ton of family in Tennessee so I take the twins down there every year and we usually connect with several Doe.