Actual weightloss in terms of poundage is more from diet than exercise (but the weight training will give you the good curves). Yeah I think with young babies you do enough running around but if you want to do cardio for a bit more of a calorie deficit ,and it makes you feel good, go for it.
Figure out how many calories you need per day to lose, count your calories, keep a food journal for a while (super-important) and write down everything you have and the quantity. Pounds lost is really calories in vs calories out but you do not need to feel like you are hungry, there are a bunch of tips along the way to stay on track (eat breakfast so you feel full, small meals throughout the day, limit night eating, etc). When in doubt, go for lean protein and veggies. Try and have carb-rich foods (sweet potatoes, oats, etc) in the mornings and before workouts and limit them the rest of the time. Try and stay close to nature and no processed stuff and artificial sweeteners and all that.
You can totally lose weight with just diet but I feel like diet and exercise go hand in hand. And this is just my opinion but I would go heavy on the weights as opposed to light. As long as you are not eating tons of calories you will not bulk up or anything. It is actually really hard for women to gain muscle usually but when we do get some it gives us nice curves, not bulk. Plus, you can eat more :)
IT can take some time. I had been athletic and slim my whole life so I thought for sure I would just bounce back after pregnancy. I nursed each of mine for a year and while breastfeeding I was a bloated, puffy mess but the first baby it took me 6 months to start seeing some results. The second baby took a year. And that is with exercise and diet. My friend who did not work out and ate Doritos and soda for breakfast was at the beach in a bikini a week after. When your body is ready it will happen.
HTH!
During breast feeding it is always advised that the lady should take 500 calories more than the calorie intake advised for her age/height/work. Now as you stopped breast feeding assessing your diet chart is important as you want to decrease that 3 kgs. As you have children you do enough work at home. To add that you do regular cardio for an hour for 6 days a week with proper diet control. Proper diet control is not dieting, it is choosing proper food. Take care!