I weighed more before I had kids than 4 years later after I gave birth to two.
Pregnancy always changes your body and recovery takes time, but it's not the reason people are overweight for years after giving birth. Healthy pregnancy weight gain (20-35lbs) only includes about 6-10lbs of fat stores for breastfeeding. Usually an extra 8lbs isn't going to be what puts someone previously in the healthy range into long term obesity. Lifestyle and diet changes when you have kids are a big part of that.
We all have different bodies. You don't have to justify how you look or your body to anyone else. No one should be shamed for being overweight, regardless of how or why they got there.