Why's my period light..?

I suspected I had a UTI on Wednesday (08/21)and Thursday and I drank a crap ton of water (over a gallon I suspect) I started my period on Thursday night - Friday morning and this is the second day. It would have been heavy by now, but its still considerably lighter than usual. Is it because I keep drinking water and cleaning myself down there that much is.not getting on the pad? I have a good amount of clots and all.. Two of my underwears have blood stains on them too, just wondering why its light. Maybe because of the water..? And I'm suddenly peeing normally now, never a foul odor, never cloudy pee or pain... What's going on?