I'm sorry to hear about your loss

Miscarriages are hard.
I actually found pregnancy to be really good for my recovery. There was a lot of nausea & vomiting at first and I had to go on diclectin to treat it, but that didn't trigger me. Having a life growing inside of me was a good way to feel connected to my body and give myself permission to be adequately nourished. I had to take care of myself in other ways too, and knowing that I was taking care of more than just myself was a good thing.
During the first trimester I had access to a maternal mental health team. They were really good at listening and figuring out solutions to my problems before they triggered a relapse. Do you have access to something like that? Your doctor might know.
Your baby won't be ashamed of your weight. He/she will see your eyes, mouth, smile, and think about all the love and warmth they carry. Your voice will soothe them to sleep, your touch will quell their fear, and your embrace will make them secure. Babies don't shame people, and they don't feel shame. Your husband isn't making this decision to have a child lightly, either, and it's something he'd want to do with someone he loves. He knows there are body changes that happen. If he knows about your disorder, he knows how hard it's going to be for you too. Can you talk to him as this is happening so he can help you through it?
Blame it on me, but know that I won't regret one iota.