WHERE DOES IT ALL GO?

[EKS PYB]

Starting earlier this year around May or so, I started getting a LOW COOLANT error on my cluster every 6 weeks or so. I have a '04 3.0 with 87k miles and never had any radiator, engine, or any major repairs done except maintenance. With all the stories I've heard on this forum, I pay VERY CLOSE ATTENTION to this ride.

I always park the X5 in the garage and look every morning and don't ever see a puddle on the floor for any leaks. So fast forward to now, I just got the error message again and I filled the radiator again like I always do but if I don't have a leak, where does it all go?

SIDE NOTE: Once in a while I do remember when I back up from the garage, there's a small 20 degree slope to get out and when I back up and stop the car on the ramp if I forgot something and park it there, turn off engine for a few minutes, when I get back in and back into the street I see a small drip on the ramp but I always thought that was from the A/C.

I'm also getting paranoid that if coolant leaks out, I am getting close to having the water pump fail on me, is that something I should look out for and get the part now?

Any advice would be greatly appreciated