Well, that's the end of the story. Finally she's been chopped and dried, buds are in the jar for curing period.
As it was my first plant, there was so many mistakes on my side that cost me a yield ( only 30g dry) and size of the plant, was 22 cm tall only.
So the main mistake was a bad water pH especially on the start of flowering but at least I found the problem on time and didn't kill the plant.
All in all I'm happy with all the lessons I got, happy with quality of the blackberry. Yield is low but I'm glad that I have something to taste at the end.