What are possible causes for menses/periods to be shorter than normal (e.g. for 1 day)?

Your guess seems right on track, and based on your symptoms you might want to be evaluated for possible polycystic ovary syndrome (PCOS). You might want to start with your general practitioner who will be able to arrange for a physical exam, some basic and diagnostic blood tests, as well as a pelvic ultrasound. In Singapore, endocrinologists and gynaecologists most commonly manage PCOS. If your symptoms and acne are indeed due to the above hormonal issue, management with lifestyle changes such as weight management, with or without oral contraceptive pills, can be of good use. Hope this helps!

For the majority of women, if you have missed your period for one week then it is a good time to test to see if you are pregnant using a urine pregnancy test kit. Some women have very irregular periods in which their menstrual cycles are more than one month long. For these cases, weekly urine pregnancy testing after a five week delay may be helpful as it may not test positive after 5 weeks delay. If the urine pregnancy tests are still negative, a more accurate way may be to test for BHCG levels (pregnancy hormones) in the blood.