Please please please be kinder to yourself!
Pregnancy weight gain is not like ‘normal’ weight gain. You are caring for your baby and doing something incredibly physically demanding - if you want carbs to help you out, have some carbs!
Remember, this weight will come off. A lot of it is the baby and his or her ‘cargo’ like placenta, extra blood, fluid, etc.
And the rest?
You will need that for recovery! And breastfeeding if you choose to. Your body is smart - it knows that it needs to hold on to weight now to help you out later, but not forever.
I have a similar ED history to what you have described and have found body image very hard in pregnancy. Throw away the scales. It really helped me when I did (well, my DH did for me). After years of daily weigh ins, I thought I would struggle without it but it actually freed me from an unhealthy habit and allowed me not to care.
You’re doing something incredible - you’re building a life! A real human being! Your weight is not important, please be proud of the amazing job you are doing :)
Your consultant will guide you on the best option for your birth. I’m afraid I don’t know much about weight and meds, but I am sure you will be fine and will be able to work out a birth plan with your hospital that is safe for you and baby x