Having super-light withdrawal bleeds (faux-periods) is very common with any kind of HBC. The high level of hormones basically tells the uterus, "Okay, ovulation's happened. Make do with whatcha got laid in!" Some uteruses stubbornly continue to build up the uterine lining, but many others don't lay in as much "carpet" (so to speak) and therefore when the hormones drop and the uterus goes, "Okay, bleed tiems nao"... it goes to see what can be thrown out, and there's only a little, or nothing at all that it wants to part with. (No bleeds 4 u!)

As for the timing of the withdrawal bleed... Your uterus is taking a while to make sure that your hormones have actually dropped, I guess. This may eventually even out -- or this may just be how your uterus reacts to the NuvaRing!

For the cramps... It could be that your uterus isn't happy to have the NuvaRing in there during orgasm, maybe? (Does it happen when you masturbate during your no-ring week?) Or, if this happened as a "PMS" sort of thing, it may just be the high level of hormones telling your body, "PMS will happen soon!" That's all just speculation, though! Sorry.

Hope some of that's useful to you!