Based on what I see here :thumbup:, I'd say the next step is investing in at least 1 speedlight, a light stand, a speedlight softbox, a 45" 5-in-1 reflector, an inexpensive off camera speedlight radio triggering system, and some time to learn how to use them before upgrading the camera body.
I agree you've got some good compositions here but the dappled light detracts from the overall impact of your images, as does the lack of separation of your subjects from the background.