I know how you feel. I got a nasty nick in the front bumper during the drive home from the dealers, and with bumpers being plastic, the stone actually makes an indentation in the plastic. I also have a couple of stone chips on the bonnet, and noticed today a little scrape on the back bumper, probably caused by a stone.
I have come to the conclusion that however much you want to keep a car perfect, it's impossible.
I bought a touch up stick the other week and have done my best, but it's not fantastic. *sigh*