Q: Coolant loss

My truck is losing coolant at first it was just that i had to fill the reservoir once every few months but its gradually gotten worse, I've had to fill it twice this week, i think it is my water pump gasket but i am not 100% sure. I checked underneath the truck and there is an orange fluid on the skid plate but i never have a puddle under my truck and my truck has never over heated or smoked which is why i think it is the water pump gasket. I looked up some stuff online and it is in a the area that is said to be where a water pump gasket would leak, i am just wondering if any of these issues i have described sound like a water pump gasket to you, i would be fine with replacing the whole water pump as well, but i am just trying to figure out if this is the problem or if it is something worse like the intake gasket or the head gaskets. Thanks

My car has 162700 miles.
My car has an automatic transmission.