I own a Kahr CWP and a KelTec PF-9. The KelTec is the samllest and lightest 9mm that I know of. It carries 7 rounds in the magizine and one in the pipe. I carry mine in the front pocket of dress slacks with an Uncle Mikes No. 4 pocket holster.
Just a warning, it does have some fairly tough recoil. The Kahr is similar in dimensions but has a square slide (similar to a Glock) and therefore it prints more than the KelTec and weighs more. If you get the KelTec you will probably want to do some minor modifications like polishing the feed ramp. I would recommend that you look at the KelTec Owners Group forum at KTOG Forum - PF-9. KelTecs are made to be carried a lot and only shot a little. They have a great warranty. If it breaks they will fix or replace it at no charge.
I hope that helps.