Have you replaced the radiator cap? After that you may have to replace the radiator if you have replaced every thing else. You should also check for a blown head gasket if you are having large fluid loss with very little showing on the ground, look at the tailpipe when running for white steem and a sweet smell. This would indicate a possible bad head gasket. You can have a shop test the antifreeze for combustion gasses too, this would also lean towards a bad head gasket. Check your oil for water also.
Jeff