Flabby baby belly needs to go BYE BYE!

Hello everyone! This is my very first time ever on a fitness site. I'm a single mom of three and just had my youngest 3 months ago. Before this past pregnancy I was 145 (I'm 5'9). At 9 months I weighed in at 210 (gestational diabetes which has now resolved) and I currently weigh 173 but the weight loss has become stagnant. I'm hoping that since I quit smoking and started exercising daily that I'll be able to shed the rest of the weight. Started smoking again after the last kiddo was born...I know, I know, shame on me! But haven't had a cig in a week and am feeling pretty motivated and determined!

Anyhoos, my goal is pretty steep...I'm exercising 30 minutes every night (start with stretches, then high impact cardio, then end with more stretches); I want to lose 15-20 pounds in three months...the diet part is going to be the hardest for me since I eat (admittedly) like a college kid:-( Dieting just seems so complicated! Counting carbs, fats, proteins...just makes me confused! Anybody have any simple dietary tips/advice to pass along?? I'd really appreciate it!

Thanks in advance and it's a pleasure to meet you all!!!