How do I stop my Beagle puppy attacking me?

Sounds like you love your beagle very much to want to help him be a better dog. I love beagles and had a little girl beagle for 13 years. I want to say in my untrained opinion what you are doing is working, so I don't really understand why the trainer does not like the methods. They are not cruel or sending the wrong message from what you have written. I have had good luck with a loud voice "no bite" command and stopping everything and walking away. It will startle them and they soon realize you don't like to participatein that kind of fun (?). Another suggestion if you are not already doing this is never ever use your hands to play near his mouth, even just a gently playful touching on his nose, etc. may be an open sign that your hands are play things. I don't know about the dominance thing except I am a female and I was talking to a male friend that owned a beagle at one time. I was sharing how my Sadie does not seem to be as loving to me as she is when a male comes around. She would go to any male and lick them on the face and just "ham it up" and show off for them. That is why I gave her a parlor name like Sadie because she was quite the flirt! He said Beagles are pack dogs (hunting in packs) and they look to the leader of the pack which he claims to be males - sounds like a story to me... Anyway, good luck and you are doing the right thing by sticking with it because if you have never had a beagle you will be forever in love with him. They are wonderful dogs and I also think he may grow out of but not for awhile if he does. You trainer may or may not like this idea but a spray bottle filled with water catches their attention very well also and after one or two times getting a little soft spray of water you will not have to actually squirt them anymore, just pick up the bottle and they will get the message.