Well, the current transistor config will produce rounded edges and produce erratic results. If you really want to keep the transistor I would do the following:
Delete - C4, R4, R5
Replace C3 with a 4.7k resistor
Change - R6 collector resistor to something like 4.7k (Not mandatory but will increase switching times)
These changes will give a much more reliable transistor logic switch. And reduce parts count in the process
Overall I commend you for putting all that together. Nice job on schematic as well.