Hmmm...I don't know that one. The NPK configuration looks ok for vegging, when N needs are higher. But I'm surprised the P is so low -- it might not be enough for flowering.
I suggest you post that as a separate question in the nutrients section. However, for where the plant is today, I don't think that the nutes are contributing to slow growth rate. If there was a deficiency, maybe, but the plant looks otherwise very healthy. So for now, I'd say you just have short, squat plant. See where it goes at 8 weeks. It will double in height again from there during flowering.
And maybe someone else will also weigh in here in the meantime!