why is it so hard

So lunch time and i cant even get that right, i agreed to some lunch, cheese and tomato on toast. My sister brings out 2 pieces of toast. I ate the first one and picked at the second one, i couldnt bring myself to eat it. I had already had a whole piece. I said to my sister "Have i eaten enough for you?" she said "i don't know, thats up to you" and did the look she does when she is annoyed at me.

I dont know how to do it. I tried, i ate something. I did it cos i didnt want to upset her, but ive upset her anyways. I cant get it right.

So now im sitting in the lounge writing this, crying and she is in the kitchen cooking some tomato sauce thing. I dont know what to do. Know i just feel even more useless for letting her down. I eat something and she gets annoyed, I dont eat anything and she gets annoyed.

I cant do it. I dont know how. I am trying, im sorry that im such a failure.

Feeling right now... like everything would be different if i wasnt around, everyone would be much happier. My sister would have no one to worry about or no one annoying her with their petty little problems. Everyone would move on, forget about me and be able to live their lives properly.