What type of workout routine and diet should one have in order to lose stomach fat?

I’m a female and I weigh 123. I’m slim overall except for my stomach, I have a lot of fat on my stomach. I began working out regularly and eating healthier in March 2006 however I still haven’t experienced any changes. I’m figuring that whatever routine and diet that I have adopted is still not enough so I’m curious as to what I should do. I plan on speaking with my doctor also but I couldn’t get an appointment for another five weeks so I wanted to get some advice in the meantime.
I was never heavy. I’ve always been slim overall l don’t remember exactly when I first started gaining the stomach fat but the first time it became really bad and noticeable was when I was in high school (4-8 years ago). I’ve tried to lose it since then but in March was the first time I heavily and regularly began working at it.