Need some guidance, please!

I'm a 68 year old breast cancer survivor and have begun edging up in my weight since my surgery a year ago.  I was starving on low calorie and have been counting carbs religiously, measuring food, reading labels, for 3 weeks with little success--although I have never been over 20 carbs daily.  I am maintaining and not feeling deprived, which is good.  Do I have to stay at 5 carbs or under for ketosis?  Any suggestions?