You can have high levels of
testosterone without all the signs of PCOS
and that can cause hirsutism. High
testosterone in women is often labelled PCOS for reasons I don't fully understand even if one has only one symptom (eg hirsutism) and no sign of polycystic ovaries. Also, menstrual irregularities, not just amenorrhea, can be related to PCOS/high testosterone.
My very thin daughter had treatment resistant acne and was found to have high testosterone, but no other signs of PCOS.