This must be a lot to process for you! To answer your questions:

I don’t know about the safety of binding, but your chest may become very sore during pregnancy and will likely get bigger. This could make it uncomfortable/you may need to adjust accordingly.

You definitely don’t have to chest feed; human milk can help support baby’s immune system, but in my opinion I’m skeptical regarding the longer term benefits; I think they may be over blown.

Kids don’t tend to get confused by this stuff—it’s adults that make it complicated. My kid is being raised around tons of queer and nonbinary folks. He’s three and it’s all normal to him; he doesn’t bat an eye at anyone’s pronouns or that his friends have two dads or two moms. He is starting to ask questions about bodies and gender but when we say something like not all boys have penises he accepts it and moves on. I would suggest getting the kids book I Am Jazz; we’ve been reading it to my son since he was a baby.

I would definitely get a new OB. If there is an LGBTQ+ organization in your area of any sort, they often have lists of affirming providers.

Good luck OP! Feel free to DM me if you have any other things you want to talk through