HI Clarissa
I believe you are supposed to lose 10% of the weight you have to lose on induction during the first two weeks. Since you have 36 lbs to lose from your beginning, losing about 5 is pretty exceptional for only being low-carbing for 2 weeks. I could be way off here, but this is what I have come to understand from the literature that I have read.
Just to relate, I also have experienced ketone strips that have shown that I was not in Ketosis, and I am sure that I definately was. I do know that your liquid consumption may have something to do with this. Sometimes I have shown a "dark" result on my ketone strip, and it has simply been an indicator that I need to drink more water! Ketones cannot be as proiminent in your urine if it is diluted with a lot of fluids(water, coffee, etc) Dont get too discouraged , I think you are doing great!