Overheating and spewing smoke out of the exhaust?

Well, here’s the synopsis:

Vehicle burns approximately one liter of antifreeze a day with only driving vehicle 30 minutes each way to work and back. Vehicle engine temperature gauge fluctuates from cold to hot and back during that drive and the interior temperature blows usually cold but hot when engine temperature shows normal range not when gauge shows hot or cold. Near the end of the drive when the vehicle is hot exhaust blows white smoke, when stopped at a stoplight it’s bad enough that it creates quite a cloud around the vehicle during my last trip.

I just finished having my radiator flushed and thermostat changed due to no hot air inside the vehicle and always showing hot on the engine temperature gauge. The rad flush seemed to work for a little while but giving variable readings and working occasionally but never showing in the red hot for 4 days and then the white smoke started even worse surrounding my vehicle in a big white cloud coming out of the exhaust. Vehicle cools down and seems to run well still, and just finished adding 2 L of antifreeze into the system again but need some advice to figure out what the real problem is. There is no milky substance in the oil at all or on the dipstick, oil looks quite clean actually which makes me wonder if it’s a head gasket issue or not, but yet it is still billowing the white smoke out of the exhaust. There are no leaks around the vehicle that I can see, so where is it all going and how do I fix it?