High Lazuli,
If this is about your Strawberry Banana grow then yes you can add big bud. When doing so you need to cut the GHE basic nutrients otherwise your EC is getting to high. And don't start with a full portion big bud, I would devide it by 3 steps. The first week 33% the second week 66% and from then till flushing the full amount.
When I was using only the GHE nutrients inside a hydro system I had this same problem. The buds just didn't swell as much as I am used to and would like.
And you do have a really great profile! Beatiful diaries and grows going on!
Happy Growing 😋