I'm really thankful to all of you for your responses! I have been increasing in strength despite the lack of soreness, I've gone up one notch in my machine exercises (chest press, lat pull down w/ wide and narrow grip, and some other things I don't know the name for). I'm also starting to outgrow my free weight sizes for bicep and tricep work, so I'm going to invest in some adjustable dumbbells. Given everyone's suggestions that I change things up, I'm thinking that I will start doing some flyes and chest presses using those dumbbells on an exercise ball.
Oh yeah, no sig other to help me here, I'm living in my parents' home to save up for medical school next year. I never knew about that negative work before, that's really interesting! Though since I started weight training only recently, I'll take your advice and save that knowledge until I've gotten some more training under my belt.