https://www.amazon.com/gp/product/B0786Z4692/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1&psc=1

It is quite a bit more, but going to a proper saling/kayaking PFD can do wonders for custom fits.

My wife who is ~50kgs found this and a few others in the stohlquist line snug in sm/xs + conformed better than a child life jacket.

if you have any access to stores like this https://kanu-connection.de/schwimmwesten,

It can do wonders to try a few on., NRS is also a well known brand that will fit better, but you do pay for the quality.