Please suggest a pattern to make this outfit, it's made from stretchy, knit fabric. Details below.

I already have a couple of them that I've purchased from this brand, but I would like to make some in other colours (they only have black and grey) I tried using one of the ones I've purchased to draft a pattern and the finished item didn't turn out very well, so I'm looking for an actual, proper pattern to use. This item is made from stretchy fabric and doesn't have any buttons or zippers. Thank you!