here are a few things in life that are guaranteed.
1) Your body and mind will change after having kids
2) You will feel mom guilt at some point in your child's life
The first thing, although it takes some time, can be managed relatively easily. Exercise, eat well, sleep well and take some time for you.
The later part, the mom guilt, is something that despite all efforts will find its way into your life whether you feel like you deserve it or not. There are many reasons behind this; conditioning (how you were raised and your parent's expectations of how you will parent), pressure from friends and your community, social media, outdated norms, discriminating laws and rules around going back to work, mat leave, and so on.