To be totally honest, you need to focus your training on "distance" running if you want to get good at the 800. I run distance events(i.e the mile, 2 mile, 800 etc.) and my training starts off with a solid mileage base before and in the beginning of the season which is basically long slow runs. As the season progresses, my coach adds in hard tempo runs which he calls the "backbone" of our fitness and speed repeats(8 400 repeats, 7 700 repeats, 6 600s, and others) which really suck, but make you a lot faster. It's hard work. And as for your times, they are respectable especially considering the type of training you did and your age and gender.