When one becomes a mom, a lot of things will change. And, the amount of confidence that you can lose in what is arguably the most pivotal time of your life is nothing but upsetting. Clothes that you wore pre-pregnancy may not fit in any way at all, skin can change (both in terms of stretch marks appearing and general condition), your mood and temperament can be all over the place and all of this is happening while you’ve got to try and look after another human being - when all you want to do is try and look after yourself and get back to rights. It’s a tough time.
You’re not alone. Almost every other mother feels like this at some point, and those who don’t show it are hiding it well. Put a bit of time into yourself and you will be back to feeling like you in no time (not the old you, though - you’ll realize you’ve come a long way since her).