11 weeks in it looks good for a big indoor sat. Get some extra holes drilled in the sides of that pot (which I think might actually be more than 10 gallons the way you describe it? I know exactly what you are talking about and it's what I was thinking of too, I just thought they had more volume than that to them) and do a nice heavy watering with excessive pH correct water (not a full flush, but definitely to runoff!) next time it's dry, then your light feeding to replace the good stuff that got washed away, and you will buy some time.
As for extra light, you COULD add side lighting but it is very late for that- up to you.