Our DS1 also has congenital heart disease; with a long hospital history, NICU and PICU stays, multiple heart operations, long term NGT, low birth weight etc etc...
One thing I would add to all the other great suggestions and your own very informed and great plan already is a "heart pillow". These are little fabric cushion pillows/shapes that my sister made up for me. They go in your bra - in your cleavage and you have a few of them so that you can always have one in your bra, a couple in the wash, and one in the cot with bubs. The thought is that your milk smell and personal smell is transfered to the cloth and then you give that one to the baby to have near their head (also great for cushioning any lines or wires they need near their skin) so they always have your smell with you. You just rotate them through the bra, baby and wash cycle. It helped me to know that Rommy always had my smell with him.
I stayed in Hospt for 8 days post birth with DS1 and sometimes went down in the night but mainly missed the overnight feeds and just was there from 6am-11pm. Then we had to go home which was over an hour away - I freaked out and the social worker found us parent accommodation in the hospital. You could enquire about this just so you have somewhere to stay if you need and have a place to nap in the day if you can. I realise it is different when you have a previous child to look after too.
I am very happy to answer any other qu you might have regarding having a child with CHD.
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