I can't say for certain but I may actually have an old underworks lying around — it's a Tri-top, size small and isn't too heavily used (but has some grubby bits where I used to keep it in my bag if I had to take it off during the day). If I can find it you'll be more than welcome to it :]
If you don't mind me asking what's your chest size? Just wanna make sure that it won't be too big or too small for you 😀