I started with kb, never used the mouse as just couldn't get to grips with it and i came from an arcade background so i played with what i was used to.
I got pretty good and quite fast on the keyboard with some weird ways of using the keys in different sequences to gain control of the faster and more difficult cars to drive.
Sad thing is once someone comes along with even a limited amount of control with a wheel, they will probably stick with you whilst you are doing your damnest!
Just keep at it. Your slow in fast out corner approach will pay off when you get a wheel, you shouldn't be surprised when you see your pb's constantly being beaten by a few seconds.