If I were you, and I mean this kindly, I would take this as an opportunity to address how much of your self esteem/self worth is tied up in your appearance - as your body has changed and will continue to change as you age. You may be able to "bounce back" from childbirth and regain your flat tum - you're only 4 months pp, give yourself a break!! But the fact this has knocked you so badly makes me wonder how you will cope with the inevitable changes other life changes - more kids, menopause, old age - will bring.
I mean from where I'm standing you describe having a strong, healthy body that literally just created human life - you're fucking incredible! What does a pouch of skin take away from that?
One of the things I most love about having had children/getting older is that for the first time in my life I genuinely don't give a fuck how I look - and I'll assure you here and now it is not size 10/12 with a slight tummy fold 😂 I am so much more than my container. And I am not here for anyone else's viewing pleasure. I am more important than that. I am me. And I am a mother. Add another stone or redistribute what's already there in an unflattering way, let my boobs descend ever closer to my belt and let hair grow in hitherto unsullied areas - that doesn't change a thing of what I am. I'm actually thinking of finally getting the tattoo I've always wanted but was waiting "until I'm thin" - I now accept I may never be thin, but I can rock a banging sleeve at any age or size 😁
Have more respect for the amazing job your body is doing, keeping you going, making and feeding your baby, aging and gaining in experience, weathering like a standing stone or an ancient tree. Surely that's better than constantly swimming against the tide of life, trying to always look like a 22 year old ingenue?