Baby weight

I now have 2,5 kilos to go before I am back at the same weight as I was before I got pregnant. If you saw me you probably wouldn't think that I could do with loosing 2,5 kg because I was quite skinny before I got knocked up. I gained like 20 kg and I couldn't have gained any less. I only ate healthy food as I completely went off anything sugary, fatty and salty.
When Little A was born, I lost about 12 kg the first few weeks without any effort, but after that it has been pretty hard. I have lost one kilo at a time in a very slow pace. I walk an hour almost all days, I practise yoga about 3 hours a week and do cardio at the gym about twice a week. And of course I am doing the 100 days ab challenge. I don't think I could do any more as my husband wants to work out as well and somebody has to watch the baby.
I don't want to go on a special diet and I am aware of what I eat and what is good for me. I have considered just accepting the extra weight, seeing that it doesn't make me overweight at all. But I don't want to. I want to be like I was before the pregnancy. Obviously, my body has changed but exactly because of that, I want to do everything I can to be like as I was before. Just because I now have stretch marks on my tummy doesn't mean I have to have a muffin top too, does it?
And it is far more environmentally friendly to loose the weight and fit into my old clothes than going out and buy a new wardrobe. Right?