Kegging beer

[joiner_8]

I kegged my suffock strong ale on the 20/11/21 the method I used wad pressure the keg to 25lb roll and shake the keg for a good 30 minutes, then put in my fridge at 6 degs.
I left it alone for two days checked the keg and topped up with co2, I then reduced the pressure to 15lb for 7 days.
Yesterday 30th of Nov I poured a half pint it had a good head but soon lost it, I have a nuka tap with a shank flow control, any tips on how I can retain the head

 

[gyurmaember]

Did you use nucleated or normal glasses? Is there enough bubbles in it despite the head?

 

[joiner_8]

It was a normal glass, I do have etched glasses from tiny rebel I'll try them thanks