Losing coolant, no visible leaks, over heating

[Koble]

I have an 04 Honda Civic EX. Was recently driving on freeway and noticed it was heating up. Pulled over, added coolant, kept driving. It started heating up again, so I turned on the heater and it went down. But temp would go up and down. About 30 min later it went almost all the way up to the red line, it was blowing cool air and not hot, I immediately shut off car.
I checked coolant level, it was bone dry! I added coolant so I could get it home and it drove fine.
It was again completely empty again! I put cardboard under car, no leaks at all.
I had someone the next day check the most obivous of things, hoses were just replaced, I bought a new radiator cap, the overflow tank had no leaks.
I havent ever noticed the fans coming on, so I turned on A/C and both fans clicked on. But when the car was overheating, I didnt hear them...
Anyways, I checked fuses they were all fine. I did notice a few bubbles when I started it with the cap off but it wasnt alot. I smelt a maple smell, idk what the indicates. I have no idea where all the coolant is going.
I am going to take it to a shop this week, but does anyone know what this could mean??? Im hoping its not the head gasket but Im thinking it is

Forgot to add- I checked oil, its normal. There isnt any white smoke coming from exhaust.

 

[Koble]

I figured that's what it was. Thank you

 

[HeX]

Are you removing the radiator cap to check fluid in the radiator itself? If you were checking the reservoir tank and not the actual radiator then its possible that the system is sucking in the extra fluid. Hsve you owned this Civic long enough to know it wasnt previously filled with water instead of coolant?