I've not checked this, but as I said I don't think the mk3 suffers from the same voltage drop issue as the mk2.
>if my bulbs are getting the voltage is there anything else i can try or look into?
worth checking that that the headlight levels are adjusted correctly, if they are pointing down then no amount of voltage or better bulbs will help.
>is it possible that my alternator is not as efficient as it needs to be when the heaters are on with the wipers, stereo and headlights? (if stereo is on 2 amps will also be running)
Start the car, turn everything on, headlights, stereo, heated windscreen's etc, and measure the battery voltage. Should still be ~14v. Also worth checking voltage between the battery neg terminal and the engine block - should be < 0.5v.
James