TMI - lack of periods

I've never been regular my periods have always been between 2 weeks and 21 months. the last 2.5yrs I've noticed when my period is more than 4mths late I start to have a smell down there, it's not awful and I can only smell it if I've pulled my underwear down after wearing them for 6+ hours. I also look late term pregnant until it comes then I go back to my usual look (I don't gain much weight but my stomach swells dramatically) I've spoken to several medical professionals but no one seems to take my concerns seriously, my stomach i really bringing my depression but no ones bothered. I have PCOS among other illnesses none related. does this happen to anyone else? I just wanna know I'm not alone.