Check for rootbound.
Next couple waterings should be plain water, then go back to the feeding you were giving before- the plant looks very healthy.
What do you have for a flowering light? It will double (at least) in size and you will end up with light penetration problems if you don't get a bigger light. I'd flower NOW and plant to transplant to a large feed pail with big drain holes drilled in it in about 2 weeks.