I didn't realise it was an auto. Yea those first 3-4 weeks are slow as hell for me with autos. Makes sense.
I would probably just get some kind of organic (or any) bloom nutrient. BUT only use it when it's needed. I've only used Kelp4Less bloom with good results years ago. It does cake over time in the bag. I'm sure there better stuff.
Since it is an auto in Ocean Forrest, it may not need more nutrients?? Never used it myself but always read stuff like that. And you can reuse your soil