MEROKEETYWomen's Summer Striped Short Sleeve T Shirt Dress Casual Tie Waist with Pockets

I am am 5'7 and 140 lbs. Should I order a medium or large?

What is the total length on a size small? "Knee length" tells me nothing.

Is this dress petite?

Would a size Small be too large for someone who's 5"0 and weighs 104 pounds? Cute dress, but I don't want to swim in it.