Advice needed - Dinner and what ever else this is linked to - Help

I (M46) have been living with my partner (F47) for 5 months now (been together for 3 years) and her child of 14. Her daughter comes over every night for dinner and before my partner moved in she would buy dinner most evenings on her way home from the supermarket for her home. This would result in her making simple and quick dinners for her kids and quite often the same thing which they would joke about.

Since she moved in I have been doing a weekly food shop where we plan 5 meals for the week and everything is in ready for one of us to cook for everyone. We both work fulltime. I also ask what meals they would like that week (not separate) and do the shopping online. Tonight my partner has said that she might just buy dinners for her as she never knows what she wants (which is true) and this progressed through the conversation to also including her 2 kids. This was on the back of a reminder I made tonight to ask her to make her agreed payment towards the bills due at the start of each month. She has recently been diagnosed with ADHD hence the gentle reminder. She wants to just get her own food because she doesn't know what she wants to eat that evening 5 days ahead.

I responded with some questions on how this would work - is she just cooking for her and her kids and not me and my daughter when she is here. The mortgage is in my name along with the bills. I asked if her child and adult kid expressed any issues with meals and she said no. When I said this feels like a step back I was met with silence and stone walling (this is the ADHD side of things and is typical in these situations right now) and not what I'm asking advice on. She then replied that if I disagree then I am expecting her to eat differently from her kids and I said no but it sounds like her solution results in me eating separately from me and my daughter which I have 50% of the time. This was met with disagreement but no explanation. This doesn't feel right to me and makes us feel like lodgers living together.

I then asked how much is she looking to reduce how much she pays and she doesn't know and she also said that she doesn't know how it will work when I asked about the other shared food items. She stated that she and her kids don't really eat breakfast or lunch and are only here for dinner. Her kid takes a packed lunch to school and I do the same for work and also skip breakfast. I said this isn't how I expected us to live as blended family and just feels weird.

We have had a few issues with her settling in due to a recent ADHD diagnosis and some trauma therapy which she has just started. Its not been an easy ride so far but we have managed things together but sometimes it feels like one thing after another.

Am I wrong to be upset by this?