You do need a break, absolutely!
What about playgroup or something like that? Will your DD play in that sort of setting so you can at least sit and have a chat with other mums?
Where's your DP in all this, does he take over sometimes?

For mealtimes, don't sweat it. Just do whatever is easiest - it doesn't matter if she eats on the floor or gets food on her clothes. Come summer you can just feed her naked & outside