Period changes

What are the signs of endometreosis and PCOS? I used to have a 5-7 day cycle with normal bleed and no cramps, now I barely bleed at all for 3 days at the most but the past 4 months it's just been spotting for about a day. April was two weeks late and cramps were soooo bad. June was a few days off and I only spotted for a day and no cramps at all. I'm due again in 5 days and I don't know what to expect this time.. I'm 25 and healthy as far as I know but why have my periods been so off?! it's like they are just slowly going away. I have had a few months where I missed my period all together. Is it because I'm getting older? Anybody else?