I have always been a shield user who struggles at parrying in the regular Souls games and I didn't find it much of an issue simply because of how generous and easy it is to adapt to using the gun.
I noticed with some friends who struggled in Bloodborne they never even tried to use the gun for parrying, which I think doomed some people because it's so easy to get good with.
I gave up attempting to stun stuff with the gun in BB.
Finished the game with all 3 endings and never found a need to touch the guns. All dodging all the time.
As with all Souls games, you have to adapt and find what works for you...