I'm 5'5", although I used to be 5'6" - besides fracturing my 12th thoracic vertebrae (aka T12) 5 or 6 years ago, I'm also 62 now, so between the 2 I've lost an inch of height (thankfully other things do not shrink with age

Anyway, I ride a Giant OCR men's small (535 mm TT).
Best regards