Yikes! Whatever you do, make some time for yourself every day. Even if it's only 10 or 15 minutes!
I don't have children, but I did have my parents and uncle for 15 years. My father had Alzheimer's and a degenerative spinal condition, so most of my mother's time and energy were devoted to him (and she had a heart condition!). My uncle was self-sufficient during most of the time my father's condition was deteriorating (12 years at home) and helped me with things around the house and took my parents to many of their medical appointments, but he definitely was no cook! *LOL*
Since I worked 50 to 60 hours weekly, I became a batch cook. I usually cooked two or three weekends per month and froze meal-size portions so I could assemble meals quickly during the week. I rarely made it home before 6:30 p.m., so we were lucky if dinner was ready by 7:00 p.m.!
Not everyone loved everything, believe me! My mother loved fairly spicey food, my father liked it bland, and my uncle was somewhere in between! I learned to make it bland and spice it up during the daily prep. And if they really didn't want what I made, there always was bread, cheese, tuna, eggs...you get the idea. Even my father would take a slice or two of cheese or some prepped veggies out of the refrigerator if he was hungry (when he was no longer able to cook or handle utensils well enough to make sandwiches)!
And one weekend a month, I did not cook. I prepped produce and made dinner from previously frozen food, but I did not cook. Period.
OP, you are wonderful for caring for your family, but they really need to take some responsibility for themselves. You can make carrot and celery sticks (or prep other favourite veggies) that everyone can eat for snacks during the week, portion canned fruit or apple sauce (worked great for us!) and other things into individual containers with lids that everyone can help themselves to throughout the day to lighten your load. Obviously, you and your DH will guide your DD's eating habits, but your parents should be a bit more self-sufficient.
Try not to feel guilty as you transition everyone--including yourself--into new patterns. There may be some bumpy roads ahead, but everyone will benefit in the end!