I can't say I have the best advice, but here are a few things to consider.
How much is your baby nursing verses eating solids? If he's mostly on solids and just nursing more for comfort than food, than dieting isn't so bad. But if he's still mostly relying on your milk for food, I wouldn't diet. There are other ways. Those other ways are what I'm going to list here.
My son, at 7 mo, is still exclusively breastfed. I try this and than now and then, but he's totally not interested. So the last thing I need right now is a reduction in milk! On the other hand, I really would like to lose weight too, and I have been losing slowly. I just tried on some skirts last night that I hadn't been able to button up 2 months ago and they buttoned. Still a little snug but wearable. But I have to be careful. Last week I think I was kind of borderline for how much I was taking in, and over the weekend my son wanted to nurse almost all the time--especially at night, which is exhausting. So I have to be careful to get enough food, even yet.
So here's what I'm doing/would recommend you do. First, don't try to lose too fast. I'm not sure where the link is, but they have proved that exercise doesn't really help with weight loss. It actually tends to make you hungrier. That doesn't mean you shouldn't exercise; just don't expect it to help you lose weight. Second, don't count calories. Eat a lot of fruits, veggies, and whole grains. The carbs in whole grains are NOT bad carbs. They are what give you energy, but they give you a steady stream of energy, not a burst like white bread/white rice/sugar do. Look for things that will boost your metabolism, like coconut oil (it is different from other fats and actually turns to energy, not fat; sugar, on the other hand, actually raises triglycerides and turns to fat). Celery takes more calories to burn than it has in it, and it's got lots of fiber. Fiber is good. It makes you feel full without lots of calories.
You should also limit your diet to certain healthy foods, and cut out junk foods period. I know this is hard to do, but I was forced to by my son, who has eczema. I can't have potatoes, soy, tomatoes, gluten, citrus, sugar... the list seems endless, really. So what I CAN eat is very limited. Sometimes I think it's because I can't find things to eat that I'm losing weight! If I didn't have my son to motivate me (knowing that he is going to break out in a rash if I eat this or that really motivates me to avoid it), I wouldn't limit myself that much. It will probably be much harder for you, but if you can cut out junk food and sweets, you will cut out a lot of bad calories.
Also, I wouldn't snack. I never do. I know it goes against what modern nutritionists say, but when I eat 2 meals a day (which I don't generally do when nursing or pregnant), I lose weight down to my ideal and then maintain it effortlessly--even if I indulge in the occasional sweet or junk food. If I get up late, like on a weekend, and eat breakfast late, I might eat a late lunch and no supper even now, but because I'm nursing I try not to make a habit of it. I'm also vegetarian, so I can eat quite a bit of food at a meal (I've heard that meat makes you feel full faster--I could be wrong, but certainly the complex protein takes longer to digest, making you feel full longer). Certain foods hold me longer than others, depending on how simple or complex they are.
Also, try to eat a lot of veggies. You can eat a lot more veggies than most people would think. Think of a Chinese stir fry. They will typically have a lot of veggies over rice with a little bit of meat. That is ideal. If you just steam some veggies and add whatever your protein source is (as a vegetarian, I add nuts, beans, egg, tofu--which I can't do now, but I used to; my son's allergic to soy), and eat that over rice. I eat as much as I want--don't bother to count calories. That's too much work. Then nothing until the next meal.
For supper, I generally don't try to eat much protein. A simple protein like yogurt or kefir is fine, but protein--especially more complex proteins like eggs or meat--take longer to digest, and I want my stomach to rest during the night. So I eat simpler food, like bread and fruit. If you eat too much or too late, it just gets stored as fat, because your body doesn't really need much energy during the night. Before I got pregnant with my daughter (I've been pregnant and/or nursing for 3 1/2 years), I rarely ate supper and as long as I stayed moderately active, I maintained my ideal weight effortlessly.
Breakfast is important. Eat heartily, and then don't snack. This boosts your metabolism, so you burn more calories, and helps prevent the mid-morning slump and keeps you from wanting to grab a snack later in the morning.
Making diet changes like I have outlined here is hard. If it's too hard, try going one small step at a time. Eat your veggies first; that will fill you up with lower calorie food. Eat whole grains. Avoid sweets (maybe allow a once-a-week indulgence, but don't overdo that: a couple cookies is fine; huge banana split isn't). Don't overdo the protein, but get some at least with breakfast and lunch. If you can't avoid snacks, eat only healthy ones (veggie sticks are a good choice). Don't drink juice. It's all sugar and no fiber. Also, don't avoid fat. It helps you feel full longer. But don't overdo it either. Cut out trans fats (that's what creates cellulite), and limit the use of animal saturated fats, especially in cooking. Drizzle olive oil and lemon on a salad for dressing, rather than getting the fat free dressings. This will help you absorb the fat-soluble vitamins and make the salad more satisfying.
So, there are a bunch of ideas. Hope it helps you and maybe some others too. :) Have fun being a mother!