You should not be doing bleeding for 1/2 an hour. The longest it has taken me is 5 minutes after the engine has warmed up. Of course, I've done this for 1/2 hour after full warmup, but I realise now that it was an overkill and unnecessary.
I should have put the time interval in my initial instructions on how to bleed the radiator. I'll ammend it now.
If you are still getting tons of bubbles like 60 or 90 minutes after you start bleeding, you've got a different problem.
I'm not exactly sure if there is a way to check if either the water pump or thermostat is working. I would suggest the following (and you should do this yourself) :
1. Try the HG solution. If it doesn't change colour (thus indicating HG failure or worse), then change both the water pump and thermostat. That should fix your problem. Either component is probably screwed or getting near screwed. And if they do need to do a head gasket job on your car, you'll need to change the wp and thermostat as well anyway.
2. Why didn't you try the HG solution already ?
When you change the water pump, change the water pump's pulley as well. They have a new pulley that is made of high temperature plastic and not the original metal. Made my engine go faster...I'm very pleased ! So this is a great way to turn a repair into an upgrade.
Of course, it might be a good idea to change the belt as well at this point.