I love cruising. I have never been ill from ship food either, and have spent over a year of my life at sea. Odd so many others have been on dodgy cruises.

Not going is clearly not an option for you, so you're obviously going to go. Others may not, their choice, but they don't need to give it imo. Doesn't help you.

I don't think your ms/hg and migraines can get worse, but have a plan in case it hits hard, like where you'll sit during a meal and where the nearest loo is. Wear bump accentuating clothes so people are extra accommodating of your needs.

And stick to small amounts of plain food. You wouldn't manage much else on land, so don't try it at sea!