Goodness, you have been through a lot of changes and stressful experiences. It sounds to me like you are having some fairly significant anxiety and definately some digestion stuff going on. I'm sorry you're pregnancy/delivery was so hard, but I think you've done a wonderful thing.
I have terrible IBS and have real issues with food/digestion/bloating and all that fun stuff. keep investigating..it helps to know as much as you can about what's going on with your body. I find that the more anxious I get the worse my appetite/digestion so I get more anxious and my tummy gets worse..and you get the picture!!
You've been through so many changes lately try not to be too hard on yourself. I can't give you any advice on being a mother but I can suggest you get some counselling around these fears. And try and keep breathing. Give bubs a hug for me and welcome to HW.