A brief side note, personally I find the kitchen too small and would remove the dining table to enlarge the kitchen instead. I understand your wish to have a casual dining area there, but without a basement you only have the utility room and storage room as storage space. We also have a utility room of your size and the two of us managed to fill it up.
After accounting for heating, etc., you can still make good use of space with well-arranged cabinets, but you naturally have to store a lot there. For us, that includes suitcases, spare tiles, inline skates, camping equipment, drinks, pantry, warranty boxes, tools, cleaning supplies, washing machine, dryer, etc. Such a utility room fills up quickly. With five people you easily have twice as much of everything.
All the kitchen items you need can never be stored in such a small kitchen area alone. That means you will have to move a lot of them to the utility room. We therefore planned the kitchen to be larger, with a lot of storage space in the kitchen island. That would be more important to me personally, since you already have a large dining table anyway.
Edit: I just saw you have a relatively large attic. You can of course store quite a bit there. But kitchen items might still be preferable to have more accessible.