Hi @Sexy_Redhead that does sound frustrating especially with the amount of effort you are putting in to make this work.
Are you stimulating the prostate while he is in your mouth? Is that what he means?
Different things will feel good at different times,
I’m sure some penis owners will give some advice but as someone who has licked a P or 2, I’ve never had anyone say that the ‘spot’ keeps moving.
If you do your regular touching and exploring, take mental notes of what is making his breath catch, what is making him shake/shudder and stimulate those parts more when he’s close.
Have a read of this thread for ideas 
Oral Sex Superbowl I have this one saved and I refer back to it every now and again.