Nice work, man! I agree with DamoRC's advice about moving the wing forward, seems like a solid start. Also you'll have to figure the entire body into the CG calculation since unlike a traditional plane it will figure heavily into "wing" loading, just the nature of flying cars. Keep iterating and don't get too down when it crashes. These are hard to get right, and you'll learn a lot more from your failures than from your successes.
Also after scrubbing through some old hard drives I found a video of an old "Red Bull" flying car I made from DTFB back in 2013. I used to race it against my friends' RC cars, which was a ton a fun.
I wish I had gotten a video of the first one of those I built, which got up to about 30mph on the pavement before it rotated straight up about 20 feet, turned around, and smashed into a thousand pieces. Good luck!