Invited to dinner, but they keep serving food i can’t eat

I’m honestly not sure if this is just a case of someone being thoughtless, or if there’s something deeper going on — but I’m getting pretty tired of it.

I have a sister-in-law who keeps inviting me over for meals that include ingredients she knows I can’t eat. This has been going on for a while now. I have diagnosed food intolerances — dairy, onions, wheat, and spicy food all make me really sick (I have IBS). I’ve explained this to her multiple times, and I’ve also said, very kindly, that I’m totally fine bringing my own food to make things easier.

But here’s the pattern:

She’ll invite me and say something like, “We’re having [insert dish that’s clearly full of things I can’t eat], and cake for dessert.” I’ll respond and say, “Thanks, I’d love to come, but I’ll bring my own food so I don’t get sick.”

Then she insists, “No, don’t bring anything — we’ll sort it out.”

And guess what? I show up, and the exact same food she originally mentioned is on the table — loaded with dairy, flour, and everything else I’ve told her I can’t eat. She doesn’t offer any alternatives or even acknowledge that the food isn’t suitable for me.

This has happened more than once. She’s even directly asked me what I can eat, and I’ve told her: plain fish or meat with vegetables, plant-based milk, and gluten-free alternatives that I know I tolerate well. Still, nothing changes.

The most recent example? She invited us for a traditional meal this weekend — sour cream porridge and cream-filled buns. I told her I’d happily bring my own versions, and again she said, “No, don’t do that.” When I asked if she’d be making dairy-free or gluten-free alternatives, she flat-out said no because the rest of her family eats everything and she doesn’t want to make two versions.

So... what exactly am I supposed to do?

Do I eat the food anyway and deal with being sick for days?

Do I bring my own food anyway and ignore her wishes?

Or do I stop attending these dinners altogether?

Part of me is starting to wonder if she just doesn’t like me and this is her way of showing it — or if she simply doesn’t take food sensitivities seriously. My husband agrees that it’s strange and has offered to talk to her about it, but I’ve asked him not to get involved (at least not yet).

Has anyone else dealt with something like this? How would you handle it without creating unnecessary drama?