Copper IUD

So I've been on the Paraguard for well over two years now. First year my period was exactly what they said it would be. Every month. Painful cramps. Heavier bleeding. About a year and a half into it I skipped a period. Then another. And now it's completely random. Some months I get one, some months I don't. Sometimes I'll spot for 3 days, heavy bleed for 2 and then spot for another 3. Then next month I may or may not have anything. does anyone know why this may be? I'm not pregnant, just took a test a couple days ago and negative. It's been 63 days since I've had a period, Although I started to spot for a couple days but then it went away and it's been a couple weeks.

Also, it seems that every time I'm about to get my period I get a yeast infection. Any suggestions as to how to avoid it? I clean well, dab dry her & make sure no moisture but it's always when that time of month is SUPPOSED to come (whether it does or doesn't).