Looking at your Flickr, it seems that you have a problem nailing focus more so than your camera being sharp. The shots that you do nail focus, the photos are plenty sharp for the lens that you are using, but there are few of those. If I were you, I would invest money in better lenses and perhaps join a photography group to improve yourself as a photographer. I see that you shot the Falcons (they need to be shot, literally). If you are in Atlanta, there is a group called the Meet and Shoot that is filled with talented photographers that can show you the ropes. Additionally, we have Aperturent and
KEH here, both of which can rent or sell you gear for you to try out. I promise you, better gear only makes taking photos easier, but it won't make you a better photographer. I'm not posting this to negatively criticize you. I think you are a bit more concerned about gear than you should be. If you are in Atlanta, I'm always looking for people to go out and do street photography with if you ever need an opportunity to shoot. I love learning from this forum, and its members have made me a better photographer.
Toodles!
Oh, and this is one of the sharpest photos that I have ever taken. It was taken with a D7100 and a Nikkor 60mm. You can download the full size and zoom 100% into her eyes. It'll cut ya. My Sony A7 can do just as good, and it has an AA filter.
Andy and Steph