Funnily enough I did very very similar project half a year ago or so:

Code: https://github.com/ghostFaceKillah/mini-self-driving-car

Writeup: https://ghostfacekillah.github.io/car.html

Good job for getting PWM steering right, I had only 3 state steering (full left, center, right) and it turned out to be quite a limitation in the end.