What could be causing my transmission fluid to be so low with no puddles or wet spots around?

I have a 2007 ford ranger with only 38k miles on it. Recently i have been having some slight 2-3 second delays when shifting to and from reverse and drive before it catches and will move. So today I decided to check my transmission fluid. Upon checking it I found there to be some there but it to be very low way below the crosshatched area. This made me think it is leaking because I know that transmission fluid doesn't burn off, but there are no spots around my garage or driveway that would indicate a leak. What could be going on?

Added (1). After waiting 30 mins from adding transmission fluid and looking under the truck i now see a small puddle.

Most likely you're checking the fluid incorrectly. I'm not sure you are, because although slow engagement of gears is a classic sign of low fluid, it would typically happen in forward AND reverse gears, not just reverse.

IF the fluid is actually low, the vacuum modulator diaphragm could be leaking. Whenever the engine is running, a small amount transmission fluid will be sucked into the intake and burned. Another possibility is that a leak in the pressurized transmission fluid line through the radiator is forcing fluid into the coolant. It could also be leaking somewhere you can't see it, especially if you haven't checked it in a long time. A last option is that it was never filled to the proper level at some time in the past, which would explain the failing reverse gear.

Check with owner's manual on the right way to check the level; running or not, operating temperature or not. Check under of the transmission and lines for ATF leak. May be a slow leak. Check inside the radiator for ATF.

Power to the power.

Are you CERTAIN that you are checking the trans fluid level correctly? In MOST cars, the engine has to be running at idle and in Neutral to check fluid level. If you pull the stick with the engine off, you WILL get a low reading.

Aside from a procedural error in checking the level, did you buy the truck used? If so it's possible that whoever had it before you had the transmission fluid changed at some point and it was refilled with too little fluid before you bought it. Running it with low fluid for however long you have been (I doubt you checked the level before this problem arose… After all, what reason would you have to check it if there were no leaks?) could have caused damage to the transmission that you're starting to notice now.

If you have owned it since new and never had the fluid changed, I'd be skeptical that the factory underfilled it. In that case I'd say you do have a leak somewhere, it's just a matter of tracking it down.