Short cycles?!

Does anyone else have really short cycles? My app is averaging my cycles to be like 17-19 days long. My other app Ovia only has one fertile day for me and its the day after my period is supposed to end? I do have pcos but I'm not wanting to take any medication right now? I have a 15 month old so I know I can get pregnant, but with these wack a** cycles I'm not so sure anymore! Ugh! :( Please tell me I'm not alone!