ill try to leave positive feedback.
i could not actually get the game to work but from what i read and understand of your project you have accomplished a lot and learned a lot in the process. my first "game" took me a year to make. i used the templates and large levels. but at some point i realized it was not going to work. but now that i have moved on and focused on programming i have made a bunch of small games all of which are better then my first large game.

Take what you have learned and start over.
sure focus on a GTA style game. maybe first make a third person shooter. then make a racing game. and then put them together and make this game again 10 times better. the worst thing you can do at this point is give up.

good luck to you.